Document:

<PAGE>

                                                                  Exhibit 10.1.9

                 [LETTERHEAD OF DUGGAN REALTY ADVISORS L.L.C.]

December 7, 1999

Mr. Satish Tiwari
Advanced Telecommunications, Inc.
730 Second Avenue South
Suite 1200
Minneapolis, MN 55402

RE:   Advanced Telecommunications, Inc.
      1500 Champa, Denver, CO
      Lease Agreement

Dear Satish:

Enclosed you will find a fully executed Lease Agreement for 1500 Champa, Suite
B-300. We are excited and look forward to Advanced Telecommunications' tenancy
at the property.

Please feel free to contact me with any property management issues that might
arise. I will work closely with Mr. Larry Vann, who will oversee the
construction of the space on behalf of Duggan Realty Advisors, L.L.C. If you can
supply me with the name and contact of your construction manager, I will forward
a construction manual accordingly.

Again, we look forward to your tenancy. If I may be of any assistance, please
contact me at (972) 980-9686 ext. 111.

Sincerely,

DUGGAN REALTY ADVISORS L.L.C

/s/ Jim Pratt

Jim Pratt
Director of Management Services

Enclosures

cc John Fefley

JWP/cmr

<PAGE>

================================================================================

                            LEASE AGREEMENT BETWEEN

                                DENVER FDS, L.P.,

                                   AS LANDLORD

                                       AND

                       ADVANCED TELECOMMUNICATIONS, INC.,

                                    AS TENANT

                             DATED November 29, 1999

================================================================================

<PAGE>

                            BASIC LEASE INFORMATION

Lease Date:           November 29, 1999

Tenant                ADVANCED TELECOMMUNICATIONS, INC., a Delaware corporation

Landlord:             DENVER FDS, L.P., a Texas limited partnership

Premises:             Suite No. B-300 in the office building commonly known as
                      1500 Champs (the "Building"), and whose street address is
                      1500 Champa, Denver, Colorado, 80202. The Premises are
                      outlined on the plan attached to the Lease as Exhibit A.
                      The land on which the Building is located (the "Land") is
                      described on Exhibit B. The term "Project" shall
                      collectively refer to the Building, the Land, and the
                      driveways, parking facilities, similar improvements and
                      easements associated with the foregoing or the operation
                      thereof.

Term:                 Approximately 123 months, commencing on the earlier of (1)
                      the date on which Tenant occupies any portion of the
                      Premises and begins conducting business therein, or (2)
                      January 1,2000 (the "Commencement Date") and ending at
                      5:00 p.m. on the last day of the 123rd full calendar month
                      following the Commencement Date, subject to adjustment and
                      earlier termination as provided in the Lease.

Basic Rent:           Subject to the conditional abatement of basic rent
                      provided in Exhibit K hereto, Tenant's initial monthly
                      installments of Basic Rent shall be $12,680.63 per month,
                      subject to adjustment as provided in the Lease.

Additional Rent:      Collectively, the following amounts, subject to adjustment
                      as provided in the Lease:

                      Chiller/Condenser Rent:        $   0    per month
                                                      ------
                      Conduit Rent:                  $   0    per diameter inch
                                                      ------  per month

                      Generator Rent:                $   0    per month
                                                      ------
                      Meet-Me Room Rent:             $   0    per month
                                                      ------
                      Transmission Equipment Rent:   $   0    per month
                                                       ------

Security Deposit:     $12,680.63

Rent:                 Basic Rent, Additional Rent, Tenant's Proportionate Share
                      of Operating Costs and all other sums that Tenant may owe
                      to Landlord or otherwise be required to pay under the
                      Lease.

Permitted Use:        General office use and the operation of telecommunications
                      equipment and facilities.

Tenant's
Proportionate
Share:                5.00%, which is the percentage obtained by dividing (a)
                      the 6,763 rentable square feet in the Premises by (b) the
                      135,189 rentable square feet in the Building. Landlord and
                      Tenant stipulate that the number of rentable square feet
                      in the Premises and in the Building set forth above shall
                      be binding upon them.

Initial
Liability
Insurance Amount:    $3,000,000.

                                       i
<PAGE>

Tenant's     For all Notices:
Address:     Advanced Telecommunications, Inc.
             730 Second Avenue South, Suite 1200
             Minneapolis, MN 55402
             Attention: Satish Tiwari
             Telephone: 612-519-4669
             Telecopy: 612-376-4414

Landlord's   For all Notices
Address:     Denver FDS, L.P.
             c/o Duggan Realty Advisors, L.L.C.
             15770 Denver Parkway, Suite 850
             Dallas, Texas 75248
             Attention: James F. Duggan
             Telephone: 972-980-9686
             Telecopy: 972-980-9705

The foregoing Basic Lease Information is incorporated into and made a part of
the Lease identified above. If any conflict exists between any Basic Lease
Information and the Lease, then the Lease shall control.

LANDLORD:                         DENVER FDS, L.P., a Texas limited partnership

                                  By:   FDS Realty Partners, L.L.C., a Texas
                                        limited liability company, as general
                                        partner

                                  By: /s/ James F. Duggan
                                     -------------------------------------------
                                  Name: James F. Duggan
                                  Title: Manager

TENANT:                           ADVANCED TELECOMMUNICATIONS, INC., a Delaware
                                  corporation

                                  By: /s/ Satish Tiwari
                                     -------------------------------------------
                                  Name: Satish Tiwari
                                  Title: Vice President

                                       ii
<PAGE>

                                TABLE OF CONTENTS
                                                                            Page
                                                                            ----

1.  Definitions and Basic Provisions .....................................     1

2.  Lease Grant ..........................................................     1

3.  Term .................................................................     1

4.  Rent .................................................................     1
    (a) Payment ..........................................................     1
    (b) Adjustments to Basic Rent and Additional Rent ....................     1
    (c) Operating Costs; Taxes; Electrical Costs .........................     2

5.  Delinquent Payment; Handling Charges .................................     4

6.  Security Deposit .....................................................     4

7.  Services .............................................................     4
    (a) Landlord's Obligations ...........................................     4
    (b) Electrical Service ...............................................     4
    (c) Janitorial Services ..............................................     5
    (d) Restoration of Services; Abatement ...............................     5

8.  Improvements; Alterations; Repairs; Maintenance ......................     5
    (a) Improvements; Alterations ........................................     5
    (b) Repairs; Maintenance .............................................     5
    (c) Performance of Work ..............................................     6
    (d) Mechanic's Liens .................................................     6

9.  Tenant's Equipment

    (a) Approval by Landlord .............................................     6
    (b) Generator
    (c) HVAC, Chillers, and Condensing Units .............................     7
    (d) Transmission Equipment ...........................................     7
    (e) Installation and Maintenance .....................................     7
    (f) Conduits and Infrastructure ......................................     8
    (g) Non-Interference .................................................     8
    (h) Indemnity ........................................................     8
    (i) Governmental Notices .............................................     8
    (j) Relocation .......................................................     8

10. Use ..................................................................     8

11. Interconnection Rights ...............................................     9

12. Co-Location ..........................................................     9

13. Assignment and Subletting ............................................     9

                                      iii
<PAGE>

    (a) Transfers .......................................................      9
    (b) Consent Standards ...............................................      9
    (c) Request for Consent .............................................     10
    (d) Conditions to Consent ...........................................     10
    (e) Cancellation ....................................................     10
    (f) Additional Compensation .........................................     10
    (g) Permitted Transfers .............................................     10

14. Insurance; Waivers; Subrogation; Indemnity ..........................     11
    (a) Insurance .......................................................     11
    (b) Waiver of Negligence; No Subrogation ............................     11
    (c) Indemnity .......................................................     12

15. Subordination; Attornment; Notice to Landlord's Mortgagee ...........     12
    (a) Subordination ...................................................     12
    (b) Attornment ......................................................     12
    (c) Notice to Landlord's Mortgagee ..................................     12
    (d) Landlord's Mortgagee's Protection Provisions ....................     12

16. Rules and Regulations ...............................................     13

17. Condemnation ........................................................     13
    (a) Total Taking ....................................................     13
    (b) Partial Taking - Tenant's Rights ................................     13
    (c) Partial Taking - Landlord's Rights ..............................     13
    (d) Award

18. Fire or Other Casualty ..............................................     13
    (a) Repair Estimates ................................................     13
    (b) Landlord's and Tenant's Rights ..................................     14
    (c) Landlord's Rights ...............................................     14
    (d) Repair Obligation ...............................................     14

19. Personal Property Taxes .............................................     14

20. Events of Default ...................................................     14

21. Remedies ............................................................     15

22. Payment by Tenant; Non-Waiver .......................................     16
    (a) Payment by Tenant ...............................................     16
    (b) No Waiver .......................................................     16

23. Landlord's Lien .....................................................     16

24. Surrender of Premises ...............................................     16

25. Holding Over ........................................................     17

26. Certain Rights Reserved by Landlord .................................     17

<PAGE>

27. Substitution Space...................................................     17

28. Miscellaneous .......................................................     18
    (a) Landlord Transfer ...............................................     18
    (b) Landlord's Liability ............................................     18
    (c) Force Majeure ...................................................     18
    (d) Brokerage .......................................................     18
    (e) Estoppel Certificates ...........................................     18
    (f) Notices .........................................................     18
    (g) Separability ....................................................     18
    (h) Amendments; and Binding Effect ..................................     18
    (i) Quiet Enjoyment .................................................     19
    (j) No Merger .......................................................     19
    (k) No Offer ........................................................     19
    (l) Entire Agreement ................................................     19
    (m) Waiver of Jury Trial ............................................     19
    (n) Governing Law ...................................................     19
    (o) Joint and Several Liability .....................................     19
    (p) Financial Reports ...............................................     19
    (q) Landlord's Fees .................................................     20
    (r) Telecommunications ..............................................     20
    (s) Confidentiality .................................................     20
    (t) Hazardous Materials .............................................     20
    (u) List of Exhibits ................................................     20

29. Other Provisions ....................................................     20

<PAGE>

                              LIST OF DEFINED TERMS

                                                                            Page
                                                                            ----

Additional Rent .........................................................      i
Affiliate ...............................................................      1
Basic Lease Information .................................................      1
Basic Rent ..............................................................      i
Building ................................................................      i
Casualty ................................................................     13
Chiller/Condenser Rent ..................................................      i
Collateral ..............................................................     16
Commencement Date .......................................................      i
Conduit Rent ............................................................      i
Damage Notice ...........................................................     13
Event of Default ........................................................     14
GAAP ....................................................................     11
Generator ...............................................................      6
Generator Rent ..........................................................      i
Hazardous Materials .....................................................     20
HVAC ....................................................................      4
including ...............................................................      1
Initial Conduits ........................................................      8
Interconnection Equipment ...............................................      9
Land ....................................................................      i
Landlord ................................................................      1
Landlord's Mortgagee ....................................................     12
Law .....................................................................      1
Laws ....................................................................      1
Lease ...................................................................      1
Lease Date ..............................................................      i
Lease Year ..............................................................      2
Legal Requirements ......................................................      6
Lines ...................................................................      8
Loss ....................................................................     11
Meet-Me Room ............................................................      9
Meet-Me Room Rent .......................................................      i
Operating Costs .........................................................      2
Operating Costs Statement ...............................................      3
Permitted Transfer ......................................................     10
Permitted Transferee ....................................................     10
Permitted Use ...........................................................      i
Premises ................................................................      i
Project .................................................................      i
Punchlist Items .........................................................    E-1
Rent ....................................................................      i
Security Deposit ........................................................      i
Taking ..................................................................     13
Tangible Net Worth ......................................................     11
Taxes ...................................................................      3
Tenant ..................................................................      1

                                       vi
<PAGE>

Tenant Delay Day .......................................................     D-2
Tenant Party ...........................................................       1
Tenant's Architect .....................................................     D-1
Tenant's Equipment .....................................................       6
Tenant's Proportionate Share ...........................................       1
Term ...................................................................       1
Total Construction Costs ...............................................     D-2
Transfer ...............................................................       9
Transmission Equipment .................................................       7
Transmission Equipment Rent ............................................       i
UCC ....................................................................      16
Work ...................................................................     D-1
Working Drawings .......................................................     D-1

                                      vii
<PAGE>

                                      LEASE

      This Lease Agreement (this "Lease") is entered into as of November ___,
1999, between DENVER FDS, L.P., a Texas limited partnership ("Landlord"), and
ADVANCED TELECOMMUNICATIONS, INC., a Delaware corporation ("Tenant").

      1. Definitions and Basic Provisions. The definitions and basic provisions
set forth in the Basic Lease Information (the "Basic Lease Information")
executed by Landlord and Tenant contemporaneously herewith are incorporated
herein by reference for all purposes. Additionally, the following terms shall
have the following meanings when used in this Lease: "Laws" means all federal,
state, and local laws, ordinances, rules and regulations, all court orders,
governmental directives, and governmental orders, and all interpretations of the
foregoing, and all restrictive covenants affecting the Project, and "Law shall
mean any of the foregoing; "Affiliate" means any person or entity which,
directly or indirectly, through one or more intermediaries, controls, is
controlled by, or is under common control with the party in question; "Tenant
Party" means any of the following persons: Tenant; any assignees claiming by,
through, or under Tenant; any subtenants claiming by, through, or under Tenant;
and any of their respective agents, contractors, employees, and invitees; and
"including" means including, without limitation.

      2. Lease Grant. Subject to the terms of this Lease, Landlord leases to
Tenant, and Tenant leases from Landlord, the Premises.

      3. Term. If the Premises are not ready for occupancy by Tenant and
Landlord is unable to tender possession of the Premises to Tenant by the
Commencement Date, then (a) Tenant's obligation to pay Basic Rent, Additional
Rent (defined below) and Operating Costs (defined below) shall be waived until
the date on which Landlord tenders possession of the Premises to Tenant (which
date will then be defined as the Commencement Date), (b) Landlord shall not be
in default hereunder or be liable for damages therefor, and (c) Tenant shall
accept possession of the Premises when Landlord tenders possession thereof to
Tenant. By occupying the Premises, Tenant shall be deemed to have accepted the
Premises in their condition as of the date of such occupancy, subject to the
performance of punch-list items that remain to be performed by Landlord, if any.
Tenant shall execute and deliver to Landlord, within ten days after Landlord has
requested the same, an amendment substantially in the form of Exhibit E hereto
confirming (1) the Commencement Date and the expiration date of the initial
Term, (2) that Tenant has accepted the Premises, and (3) that Landlord has
performed all of its obligations with respect to the Premises (except for
punch-list items specified in such letter).

      4. Rent.

            (a) Payment. Tenant shall timely pay to Landlord Rent, without
deduction or set off, at Landlord's address provided for in this Lease or as
otherwise specified by Landlord and shall be accompanied by all applicable state
and local sales or use taxes. Basic Rent, adjusted as herein provided, shall be
payable monthly in advance. Tenant's obligation to pay Basic Rent, Additional
Rent and Tenant's Proportionate Share of Operating Costs shall be abated for the
first three months of the Term. The first monthly installment of Basic Rent
(i.e., the fourth month of the Term) shall be payable contemporaneously with the
execution of this Lease; thereafter, Basic Rent shall be payable on the first
day of each month beginning on the first day of the fifth full calendar month of
the Term. The monthly Basic Rent for any partial month at the beginning of the
Term shall equal the product of 1/365 of the annual Basic Rent in effect during
the partial month and the number of days in the partial month from and after the
Commencement Date, and shall be due on the Commencement Date. Tenant shall pay
Additional Rent at the same time and in the same manner as Basic Rent

            (b) Adjustments to Basic Rent and Additional Rent. Beginning on the
first day of the second Lease Year (defined herein) and again on the first day
of each succeeding Lease Year thereafter, the

                                       1
<PAGE>

monthly Basic Rent and Additional Rent shall be increased to an amount equal
to the product of (1) 103% times (2) the monthly Basic Rent and Additional
Rent last payable hereunder for the immediately preceding Lease Year. As used
herein, the "Lease Year" means each successive 12-month period beginning on
the Commencement Date (and if the Commencement Date does not occur on the
first day of a calendar month, the first Lease Year shall also include the
period from the Commencement Date to the first day of the next calendar
month).

            (c) Operating Costs; Taxes; Electrical Costs.

                  (1) Tenant shall pay Tenant's Proportionate Share of Operating
      Costs (defined herein) during each calendar year of the Term. If the Term
      begins on a day other than the first day of a calendar year or ends on a
      day other than the last day of a calendar year, then, for purposes of
      determining Tenant's obligations under this Section 4.(c), the Operating
      Costs for such year shall be determined by multiplying the aggregate
      Operating Costs for the entire year in question by a fraction whose
      numerator is the number of days in the Term falling within such year and
      whose denominator is the number of days in such year, and Tenant shall pay
      Tenant's Proportionate Share thereof. Landlord may make a good faith
      estimate of the Operating Costs to be due by Tenant for any calendar year
      or part thereof during the Term, and Tenant shall pay to Landlord, on the
      first day of each calendar month thereafter, an amount equal to the
      estimated Operating Costs for such calendar year or part thereof divided
      by the number of months therein. From time to time, Landlord may estimate
      and re-estimate the Operating Costs to be due by Tenant and deliver a copy
      of the estimate or re-estimate to Tenant. Thereafter; the monthly
      installments of Operating Costs payable by Tenant shall be appropriately
      adjusted in accordance with the estimations so that, by the end of the
      calendar year in question, Tenant shall have paid all of the Operating
      Costs as estimated by Landlord. Any amounts paid based on such an estimate
      shall be subject to adjustment as herein provided when actual Operating
      Costs are available for each calendar year.

                  (2) The term "Operating Costs" shall mean all expenses and
      disbursements (subject to the limitations set forth below) that Landlord
      incurs in connection with the ownership, operation, and maintenance of the
      common areas of the Project, determined in accordance with sound
      accounting principles consistently applied, including, but not limited to,
      the following costs:

                              (A) wages and salaries (including management fees)
                  of all employees engaged in the operation, maintenance, and
                  security of the Project, including taxes, insurance and
                  benefits relating thereto;

                              (B) all supplies and materials used in the
                  operation, maintenance, repair, replacement, and security of
                  the Project;

                              (C) costs for improvements made to the Project
                  which, although capital in nature, are expected to reduce the
                  normal operating costs (including all utility costs) of the
                  Project, as well as capital improvements made in order to
                  comply with any law hereafter promulgated by any governmental
                  authority, as amortized over the useful economic life of such
                  improvements as determined by Landlord in its reasonable
                  discretion;

                              (D) cost of all utilities, including fuel, gas,
                  electricity (except electrical costs reimbursed to Landlord by
                  the Building's tenants, other than pursuant to a provision
                  similar to this Section 4.(c)), water, sewer, telephone and
                  other services;

                              (E) insurance expenses;

                                       2
<PAGE>

                              (F) all taxes, assessments, and governmental
                  charges whether federal, state, county or municipal, and
                  whether they be by taxing districts or authorities presently
                  taxing or by others, subsequently created or otherwise, and
                  any other taxes and assessments attributable to the Project
                  (or its operation) (collectively, "Taxes"), excluding,
                  however, penalties and interest thereon and federal and state
                  taxes on income; if the present method of taxation changes so
                  that in lieu of the whole or any part of any Taxes, there is
                  levied on Landlord a capital tax directly on the rents
                  received therefrom or a franchise tax, assessment, or charge
                  based, in whole or in part, upon such rents for the Project,
                  then all such taxes, assessments, or charges, or the part
                  thereof so based, shall be deemed to be included within the
                  term "Taxes" for purposes hereof. Taxes shall include the
                  costs of consultants retained in a effort to lower taxes and
                  all costs incurred in disputing any taxes or in seeking to
                  lower the tax valuation of the Project. For property tax
                  purposes, Tenant waives all rights under applicable Law to
                  protest or appeal the appraised value of the Project or any
                  part thereof; and to receive notices of reappraisement;

                              (G) fair market rental and other costs with
                  respect to the management office for the Building;

                              (H) repairs, replacements, and general maintenance
                  of the Building, including janitorial services (with respect
                  to common areas only);

                              (I) service or maintenance contracts with
                  independent contractors for the operation, maintenance,
                  repair, replacement, or security of the Building (including,
                  without limitation, alarm service, window cleaning, and
                  elevator maintenance); and

                              (J) costs of professional services rendered for
                  the general benefit of the Project

                  Operating Costs shall not include costs for (i) capital
      improvements made to the Project, other than capital improvements
      described in Section 4.(c)(2)(C) and except for items which are generally
      considered maintenance and repair items, such as painting of common
      areas, replacement of carpet in elevator lobbies, and the like; (ii)
      repair, replacements and general maintenance paid by proceeds of insurance
      or by Tenant or other third parties; (iii) interest, amortization or other
      payments on loans to Landlord; (iv) depreciation; (v) leasing commissions;
      (vi) legal expenses for services, other than those that benefit the
      Building tenants generally (e.g., tax disputes); (vii) renovating or
      otherwise improving space for occupants of the Building or vacant space in
      the Building; and (viii) federal income taxes imposed on or measured by
      the income of Landlord from the operation of the Project

                  (3) By April 1 of each calendar year, or as soon thereafter as
      practicable, landlord shall finish to Tenant a statement of Operating
      Costs for the previous year, adjusted as provided in Section 4.(c)(4) (the
      "Operating Costs Statement"). If the Operating Costs Statement reveals
      that Tenant paid more for Operating Costs than the actual amount of
      Tenant's Proportionate Share thereof for the year for which such statement
      was prepared, Landlord shall promptly credit or reimburse Tenant for such
      excess; likewise, if Tenant paid less than Tenant Proportionate Share of
      Operating Costs, then Tenant shall pay Landlord such deficiency within 30
      days after delivery of the Operating Costs Statement in question.

                  (4) With respect to any calendar year or partial calendar year
      in which the Building is not occupied to the extent of 100% of the
      rentable area thereof; the Operating Costs for such period

                                       3
<PAGE>
     shall, for the purposes hereof be increased to the amount which would have
     been incurred had the Building been occupied to the extent of 100% of the
     rentable area thereof.

      5. Delinquent Payment; Handling Charges. All past due payments required of
Tenant hereunder shall bear interest from the date due until paid at the lesser
of eighteen percent per annum or the maximum lawful rate of interest;
additionally, Landlord, in addition to all other rights and remedies available
to it, may charge Tenant a fee equal to 5% of the delinquent payment to
reimburse Landlord for its cost and inconvenience incurred as a consequence of
Tenant's delinquency. In no event, however, shall the charges permitted under
this Section 5 or elsewhere in this Lease, to the extent they are considered to
be interest under applicable Law, exceed the maximum lawful rate of interest.

      6. Security Deposit. Contemporaneously with the execution of this Lease,
Tenant shall pay to Landlord the Security Deposit, which shall be held by
Landlord to secure Tenant's performance of its obligations under this Lease. The
Security Deposit is not an advance payment of Rent or a measure or limit of
Landlord's damages upon an Event of Default (defined in Section 20). Landlord
may, from time to time following an Event of Default and without prejudice to
any other remedy, use all or a part of the Security Deposit to perform any
obligation Tenant fails to perform hereunder. Following any such application of
the Security Deposit, Tenant shall pay to Landlord on demand the amount so
applied in order to restore the Security Deposit to its original amount.
Provided that Tenant has performed all of its obligations hereunder, Landlord
shall, within 30 days after the Term ends, return to Tenant the portion of the
Security Deposit which was not applied to satisfy Tenant's obligations. The
Security Deposit may be commingled with other funds, and no interest shall be
paid thereon. If Landlord transfers its interest in the Premises and the
transferee assumes Landlord's obligations under this Lease, then Landlord may
assign the Security Deposit to the transferee and Landlord thereafter shall have
no further liability for the return of the Security Deposit.

      7. Services.

          (a) Landlord's Obligations. Landlord shall use all reasonable efforts
to finish to Tenant (1) water at those points of supply provided for general
use of tenants of the Building in the common areas thereof; (2) heated and
refrigerated air conditioning ("HVAC") as appropriate to the common areas of
the Building, at such temperatures and in such amounts as are standard for
comparable buildings in the vicinity of the Building; (3) janitorial service
to the common areas of the Building on weekdays, other than holidays, for
Building-standard installations and such window washing as may from time to
time be reasonably required; and (4) elevator(s) for ingress and egress to
the floor on which the Premises are located, in common with other tenants,
provided that Landlord may reasonably limit the number of operating elevators
during non-business hours and holidays. Landlord shall maintain the common
areas of the Building in reasonably good order and condition, except for
damage caused by a Tenant Party. If Tenant desires any of the services
specified in this Section 7.(a) at any time other than the times herein
stated, such services shall be supplied upon the written request of Tenant
delivered to Landlord before 3:00 p.m. on the business day preceding such
extra usage, and Tenant shall pay to Landlord the cost of such services, plus
an administrative fee equal to 15% of the cost thereof, within ten days after
Landlord has delivered to Tenant an invoice therefor. The costs incurred by
Landlord in providing after-hour HVAC service shall include costs for
electricity, water, sewage, water treatment, labor, metering, filtering, and
maintenance reasonably allocated by Landlord to providing such service.

          (b) Electrical Service. All electrical power for the Premises and for
the operation of Tenant's Equipment (defined herein) shall be provided directly
to Tenant from an electrical service provider through a direct utility hookup to
the Premises (or through submetering at Landlord's sole discretion) to be
furnished, installed and maintained at Tenant's sole expense. Without limiting
the generality of the foregoing, Tenant, at its sole cost and expense, shall pay
the cost of all equipment, meters, switches, transformers, feeders, risers, and
wiring required to provide electrical service to the Premises and Tenant's
Equipment (collectively, the

                                       4
<PAGE>

"Electrical Equipment"). Landlord will provide Tenant's electrical service
provider reasonable access to the Building to install, at a location therein
acceptable to Landlord, the transformer required to furnish electrical service
to the Premises. The installation of all Electrical Equipment shall be done only
in accordance with plans and specifications that have been previously submitted
to and approved by Landlord in writing and shall be subject to the provisions of
Section 8. Whenever Tenant is required to pay the cost of any Electrical
Equipment under the foregoing provisions, the cost thereof shall include the
cost of installation, operation, use and maintenance of such Electrical
Equipment. If electrical service to the Premises or for Tenant's Equipment is
submetered, the submeter shall be read by Landlord and Tenant shall pay to
Landlord the cost of such electrical service based on rates charged for such
service by the utility company furnishing such service, including all fuel
adjustment charges, demand charges and taxes. Landlord makes no representation
or warranty to Tenant concerning the quantity or availability of electrical
power or electrical service to the Premises or for Tenant's Equipment and shall
not be liable for any damages (direct or consequential) caused by, and in no
event shall Rent abate by reason of, the interruption, insufficiency,
unavailability or discontinuance of such electric service.

          (c) Janitorial Services. Notwithstanding any contrary provision
herein, Tenant, at its sole expense, shall provide its own janitorial services
to the Premises (including trash removal) and shall maintain the Premises in a
clean, safe and operable condition as required by Section 8.(b). If Tenant fails
to provide janitorial services to the Premises in compliance with the foregoing,
Landlord, in addition to any other rights and remedies available to it, may
provide such janitorial services, and Tenant shall pay to Landlord the cost
thereof, plus an administrative fee equal to 15% of such cost, within ten days
after Landlord delivers to Tenant an invoice therefor.

          (d) Restoration of Services; Abatement. Landlord shall use reasonable
efforts to restore any service required of it under Section 7.(a) that becomes
unavailable; however, such unavailability shall not render Landlord liable for
any damages caused thereby, be a constructive eviction of Tenant, constitute a
breach of any implied warrant, or, except as provided in the next sentence,
entitle Tenant to any abatement of Tenant's obligations hereunder. If, however,
Tenant is prevented from using the Premises for more than 25 consecutive
business days because of the unavailability of any such service and such
unavailability was not caused by a Tenant Party, then Tenant shall, as its
exclusive remedy he entitled to a reasonable abatement of Rent for each
consecutive day (after such 25-day period) that Tenant is so prevented from
using the Premises. Landlord shall have no obligation to restore any electrical
service that becomes unavailable to the Premises and such unavailability shall
not render Landlord liable for any damages caused thereby, be a constructive
eviction of Tenant, constitute a breach of any implied warranty or entitle
Tenant to any abatement of Tenant's obligations hereunder unless caused by
Landlord's gross negligence or willful misconduct.

     8. Improvements; Alterations; Repairs; Maintenance.

          (a) Improvements; Alterations. Improvements to the Premises shall be
installed at Tenant's expense only in accordance with plans and specifications
which have been previously submitted to and approved in writing by Landlord. No
alterations or physical additions in or to the Premises may be made without
Landlord's prior written consent, which shall not be unreasonably withheld or
delayed; however, Landlord may withhold its consent to any alteration or
addition that would affect the Building's structure or its HVAC, plumbing
electrical, or mechanical systems. Tenant shall not paint or install lighting or
decorations, signs, window or door lettering, or advertising media of any type
on or about the Premises without the prior written consent of Landlord, which
shall not be unreasonably withheld or delayed; however, Landlord may withhold
its consent to any such painting or installation which would affect the
appearance of the exterior of the Building or of any common areas of the
Building. All alterations, additions, and improvements shall be constructed,
maintained, and used by Tenant, at its risk and expense, in accordance with all
Laws; Landlord's approval of the plans and specifications therefor shall not be
a representation by Landlord that such alterations, additions, or improvements
comply with any Law.

                                        5
<PAGE>

          (b) Repairs; Maintenance. Tenant shall maintain the Premises in a
clean, safe, and operable condition, and shall not permit or allow remaining any
waste or damage to any portion of the Premises. Tenant shall repair or replace,
subject to Landlord's direction and supervision, any damage to the Building
caused by a Tenant Party. If Tenant fails to make such repairs or replacements
within 15 days after the occurrence of such damage, then Landlord may make the
same at Tenant's cost. If any such damage occurs outside of the Premises, then
Landlord may elect to repair such damage at Tenant's expense, rather than having
Tenant repair such damage. The cost of all repair or replacement work performed
by Landlord under this Section 8 shall be paid by Tenant to Landlord within ten
days after Landlord has invoiced Tenant therefor.

          (c) Performance of Work. All work described in this Section 8 shall be
performed only by Landlord or by contractors and subcontractors approved in
writing by Landlord. Tenant shall cause all contractors and subcontractors to
procure and maintain insurance coverage naming Landlord, Landlord's agents and
their respective Affiliates, as additional insureds against such risks, in such
amounts, and with such companies as Landlord may reasonably require. All such
work shall be performed in accordance with all Laws and in a good and
workmanlike manner so as not to damage the Building (including the Premises, the
structural elements, and the plumbing, electrical lines, or other utility
transmission facility). All such work which may affect the Building's HVAC,
electrical, plumbing other mechanical systems, or structural elements must be
approved by the Building's engineer of record, at Tenant's expense and, at
Landlord's election, must be performed by Landlord's usual contractor for such
work.

          (d) Mechanic's Liens. Tenant shall not permit any mechanic's liens to
be filed against the Premises or the Project for any work performed, materials
furnished, or obligation incurred by or at the request of Tenant. If such a lien
is filed, then Tenant shall, within ten days after Landlord has delivered notice
of the filing thereof to Tenant, either pay the amount of the lien or diligently
contest such lien and deliver to Landlord a bond or other security reasonably
satisfactory to Landlord, If Tenant fails to timely take either such action,
then Landlord may pay the lien claim, and any amounts so paid, including
expenses and interest, shall be paid by Tenant to Landlord within ten days after
Landlord has invoiced Tenant therefor.

     9. Tenant's Equipment.

          (a) Approval by Landlord. Tenant shall, at its sole cost and expense,
provide to Landlord for its prior written approval, detailed plans and
specifications for the installation by Tenant within and outside the Premises of
all communications switching equipment and associated ancillary equipment used
in Tenant's business operations, including the Generator (defined below), the
Transmission Equipment (defined below), HVAC equipment, chillers and condensing
units, and all conduits installed by or for Tenant as described below
(collectively, "Tenant's Equipment").

          (b) Generator. Subject to the provisions of Section 8 and Tenant's
payment of Generator Rent, Tenant may (1) install, operate, and maintain one
generator within the Project (in the area described in the next sentence) for
Tenant's business operations for emergency back-up purposes, which generator
will require either a propane, diesel or natural gas fuel system, as more
particularly described in Tenant's plans and specifications, and (2) store fuel
on the Premises or elsewhere within the Project (as described below), in such
amounts as Tenant reasonably determines necessary for Tenant's generator (the
"Generator," which defined term shall also refer to all related equipment
including the Generator Fuel Tanks, as defined below). The Generator shall be
installed at a location on the roof over the third floor of the Building
reasonably acceptable to Landlord within the area shown on Exhibit A-2, provided
that the installation, maintenance, use, and operation thereof complies with all
Laws, and Tenant receives all approvals, consents, and permits required under
applicable Law before the installation, maintenance, use, and operation thereof.
To the extent that any permits or registrations are required for the
installation or operation of the Generator, they shall be obtained by Tenant in
Tenant's name. The fuel for the Generator shall be stored in tank located above
ground in the portion of the Premises located

                                        6
<PAGE>

in the basement of the Building (the "Generator Fuel Tank"). Tenant may lease
from Landlord an additional 1,392 rentable square feet in the basement of the
Building (the "Expansion Space") at a location reasonably acceptable to Tenant
and Landlord for the purpose of installing its Generator Fuel Tank. If Tenant
timely exercises its option to lease the Expansion Space, then (a) possession of
the Expansion Space shall be delivered to Tenant in an "AS-IS" condition on the
earlier of five business days after Tenant's written election to lease the
Expansion Space or the date on which Tenant occupies the Expansion Space with
Landlord's prior written consent, and (b) Tenant and Landlord shall execute an
amendment to this Lease including the Expansion Space in the Premises on the
same terms as this Lease, except as follows: (1) the rentable square feet of the
Premises shall be increased by the rentable square feet in the Expansion Space;
(2) the per rentable square foot Basic Rent for the Expansion Space shall be
equal to $22.50 per rentable square foot per year; and (3) Landlord shall not
provide to Tenant any allowances (e.g. moving allowance, construction allowance,
and the like) or other tenant inducements. Before beginning the installation of
the Generator, Tenant shall deliver to Landlord final plans and specifications
therefor prepared by an engineer reasonably approved by Landlord and setting
forth in detail the design, location, size, and method of installation
(including without limitation, separation walls, interstitial monitoring and
ventilation system) for Landlord's review and approval, with approval shall not
be unreasonably withheld, conditioned or delayed, together with evidence
reasonably satisfactory to Landlord of compliance thereof with all Laws. Copies
of such final plans and specifications shall be initialed by Landlord (unless
deemed approved) and by Tenant, and promptly attached to and incorporated into
this Lease by reference in place of Exhibit A-2. Landlord's approval of any such
plans and specifications shall not constitute a representation or warranty by
Landlord that such plans and specifications comply with all Laws; such
compliance shall be the sole responsibility of Tenant. The Generator shall be
installed and screened in a manner acceptable to Landlord, and no underground
storage tanks may be installed or used in connection therewith. Upon reasonable
approval of the plans and specifications therefor and the location thereof,
Tenant may install the Generator provided that such work is coordinated with
Landlord and is performed in a good and workmanlike manner, in accordance with
all Laws and the plans and specifications therefor and in a manner so as not to
damage the Building or materially interfere with the use of any portion of the
Building while such installation is taking place; thereafter, Tenant shall use,
maintain, and operate the Generator in a good, clean, and safe condition and in
accordance with all Laws. Provided no Event of Default exists, Tenant may remove
the Generator at any time during the Term, and shall remove the Generator at the
end of the Term as provided in Section 24. Tenant shall repair all damage caused
by the installation, use, maintenance, operation, or removal of the Generator
and, upon its removal, restore the portion of the Building grounds where it was
located to its condition immediately before the installation thereof, normal
wear and tear and damage by casualty excepted. If Tenant fails to repair such
damage and restore such Building grounds within 30 days after Landlord's
request, Landlord may perform such work, and Tenant shall pay to Landlord all
reasonable costs incurred in connection therewith within 30 days after
Landlord's written request therefor. Tenant shall properly fuel and immediately
remove from the area surrounding the Generator any spills or other leaks of
fluid from the Generator. Additionally, Tenant shall ensure that the Generator
is properly exhausted at all times so no odors emanate therefrom. The Generator
shall be installed, used, maintained, operated, and removed at Tenant's risk and
expense. All testing of the Generator shall be performed after normal business
hours and must be coordinated with Landlord.

          (c) HVAC, Chillers, and Condensing Units. Subject to the provisions of
Section 8 and Tenant's payment of Chiller/Condenser Rent, Tenant shall have the
right to install and maintain, at Tenant's sole cost and expense, supplemental
HVAC equipment in the Premises ("Tenant's HVAC Equipment") ad chillers, dry
coolers and/or condensing units (collectively, the "Cooling Equipment) and upon
the roof of the Building at a location reasonably acceptable to Landlord within
the area shown on Exhibit A-3, and shall have a route reasonably acceptable to
Landlord for glycol or similar piping from Tenant's HVAC Equipment to the
Cooling Equipment Copies of the final plans and specifications evidencing the
specific location within the area shown on Exhibit A-3 shall be initialed by
Landlord (unless deemed approved) and by Tenant, and promptly attached to and
incorporated into this Lease by reference in place of Exhibit A-3. Tenant shall
comply with all Laws in

                                      7
<PAGE>

connection with the installation, maintenance, use and operation of Tenant's
HVAC equipment and the Cooling Equipment.

          (d) Transmission Equipment. Subject to the provisions of Section 8 and
Tenant's payment of Transmission Equipment Rent, Tenant shall have the right at
its sole cost and expense, to install and maintain an antenna, satellite dish
and/or other transmission facilities, including all related wiring (the
"Transmission Equipment) at a location on the Building acceptable to Landlord.
Tenant shall comply with all Legal Requirements applicable to the installation,
operation, use and maintenance of the Transmission Equipment and rules and
regulations of the Building. Tenant, at its sole cost and expense, shall obtain
and maintain all necessary permits and licenses required for the installation,
operation and maintenance of the Transmission Equipment. Tenant shall maintain
the Transmission Equipment in a manner so as not to interfere with the
Building's operations or the operations of any other tenant or occupant of the
Building or any other person providing services to or in connection with the
Building or its occupants.

          (e) Installation and Maintenance. Tenant shall, at its sole expense
and risk, install Tenant's Equipment in a good and workmanlike manner in
compliance with plans and specifications therefor approved by Landlord and all
Legal Requirements and Section 8. Tenant shall be solely responsible for the
adequacy and safety of the installation, operation, maintenance, repair and
removal of Tenant's Equipment. Tenant shall be solely liable for any damage or
injury arising out of the installation, operation, maintenance, repair and
removal of Tenant's Equipment; including any damage to the Premises, the Project
or any property of other tenants or occupants of the Building. Tenant shall pay
to Landlord on demand the cost of repairing any damage to the Project caused by
such installation, operation, maintenance, repair or removal of Tenant's
Equipment, and all costs incurred by Landlord in reviewing and inspecting the
installation and operation of Tenant's Equipment, including the costs and fees
of any consulting engineers, roofers, or other contractors hired by Landlord for
such purpose.

          (f) Conduits and Infrastructure. Subject to the provisions of Section
8 and Tenant's payment of Conduit Rent, Tenant shall have the right, at its sole
cost and expense, as part of its installation of Tenant's Equipment and the
Initial Improvements, to upgrade the Building's infrastructure, including fire
suppression system, electrical, water and telecommunications conduits. Subject
to the provisions of Section 8, Tenant (1) may install a reasonable number of
conduits as shown and described in Tenant's plans and specifications from the
Premises to the Meet-Me Room (defined below), the Generator and the Building
electrical room, which will be installed by Tenant at Tenant's sole cost and
expense in a good and workmanlike manner and in compliance with applicable Laws,
(2) may install pipe chases from the basement of the Building to the southwest
corner of the roof above the third floor of the Building for the supply and
return of fuel lines from the Generator Fuel Tank to the Generator, and (3) may,
at Tenant's sole cost and expense, install additional conduits for power, four
4" conduits for Tenant's HVAC Equipment, two 4" conduits directly from the
Premises to Champa Street and two 4" conduits directly from the Premises to 15th
Street but only for use by Tenant in the operation of its business to
interconnect with other telecommunications providers, in each case in locations
reasonably approved by Landlord (all of the foregoing conduits are herein
collectively referred to as the "Initial Conduits"). If Landlord permits Tenant
to install or use conduits or equivalent cable runs in excess of the Initial
Conduits, Tenant shall pay Conduit Rent equal to the fair market rate, as
reasonably determined by Landlord, for each diameter inch that exceeds the
Initial Conduits. The foregoing provisions shall apply to all conduits and
equivalent cable runs installed and/or used by Tenant, including those for
interconnection rights under Section 11 and for Tenant's Equipment and
Electrical Equipment that exceeds the Initial Conduits. The Initial Conduits and
any other conduits and cable runs that Tenant is permitted to install or use
under the foregoing provisions are herein collectively referred to as "Tenant's
Conduits." Landlord shall have no liability for damages arising from, and
Landlord does not warrant that Tenant's use of any communications or computer
wires, cables and related devices (collectively, the "Lines") in or serving the
Premises will be free from any (A) eavesdropping or

                                        8
<PAGE>

wiretapping by unauthorized parties, provided that Landlord shall not have
authorized or permitted such acts unless required by Law, (B) failure of any
Lines to satisfy Tenant's requirements, or (C) shortages, failures, variations,
interruptions, disconnections, loss or damage caused by the installation,
operation, maintenance, repair or removal of the Lines by or for other tenants
or occupants of the Building except to the extent caused by Landlord's gross
negligence or willful misconduct.

          (g) Non-Interference. Tenant shall operate Tenant's Equipment in such
a manner as not to interfere with the maintenance or operation of the Building
including the Building's HVAC, plumbing, electrical or mechanical systems or the
operation of any existing radio or telecommunications equipment operated on or
from the Building In the event of any such interference, Tenant shall suspend
operation of Tenant's Equipment within 24 hours after written notice thereof
from Landlord and shall not resume operation of Tenant's Equipment until such
operation is in strict compliance with the foregoing requirements.

          (h) Indemnity. Tenant's indemnification obligations under Section
14.(c) shall also apply to any Loss arising from Tenant's installation,
operation, maintenance, repair or removal of Tenant's Equipment.

          (i) Governmental Notices. Tenant shall promptly provide Landlord
copies of any notices, demands or directives received by Tenant from any
governmental authority or insurance carrier in connection with the installation,
operation, maintenance, repair or removal of Tenant's Equipment, and Tenant
shall promptly comply with all such notices, demands and directives at its sole
cost and expense. Such cost shall include all equipment and transport related to
the equipment.

          (j) Relocation. Notwithstanding any contrary provision herein,
Landlord shall have the right, at its option and sole cost, upon not less than
60 days prior written notice to Tenant, to relocate any of Tenant's Equipment to
such other location or locations within the Project as Landlord may designate.
Tenant shall cooperate with Landlord to enable Landlord to accomplish any such
relocation.

     10. Use. Tenant shall occupy and use the Premises only for the Permitted
Use and shall comply with all Laws relating to the use, condition, access to,
and occupancy of the Premises. The population density within the Premises as a
whole shall at no time exceed one person for each 300 rentable square feet in
the Premises. The Premises shall not be used for any use which is disreputable,
creates extraordinary fire hazards, or results in an increased rate of insurance
on the Building or its contents, or for the storage of any Hazardous Materials.
If, because of a Tenant Party's acts, the rate of insurance on the Building or
its contents increases, then such acts shall be an Event of Default, Tenant
shall pay to Landlord the amount of such increase on demand, and acceptance of
such payment shall not waive any of Landlord's other rights. Tenant shall
conduct its business and control each other Tenant Party so as not to create any
nuisance or unreasonably interfere with other tenants or Landlord in its
management of the Building.

     11. Interconnection Rights. Landlord acknowledges that the nature of
Tenant's business may require it to interconnect with other telecommunications
companies that may also be located in the Building. To facilitate such
interconnection and subject to the payment of Conduit Rent and Meet-Me Room
Rent, Landlord agrees that it will make available to Tenant space for Tenant to
install and maintain, at its sole expense, one relay rack; cage or cabinet in
the conduit room for the Building (the "Meet-Me Room"). The location, size and
configuration of space available to Tenant in the Meet-Me Room shall be
determined by Landlord in its sole discretion and which is reasonably acceptable
to Tenant. Subject to the payment of Conduit Rent and Meet-Me Room Rent and
Landlord's prior written approval, Tenant may (1) install, maintain and use
cables, conduits, wires, cable ducts, telephone closets and ladder racks for the
conduct of its business between the Premises and other parts of the Building and
(2) directly connect to, interface with, or otherwise attach to the lines and
facilities of the public utilities finishing electrical or telephone services to
the Building, for additional electrical energy and telephone connections to the
Premises. The cost of installation, operation, use and maintenance of the

                                       9
<PAGE>

foregoing modifications or improvements (including telecommunications cabinets,
relays, and cages) shall be borne solely by Tenant. All modifications or
improvements just described are herein collectively referred to as the
"Interconnection Equipment." Tenant, at its sole cost and expense, shall comply
with all Legal Requirements relating to the installation, operation,
maintenance, repair or removal of the Interconnection Equipment. Tenant's
indemnification obligations under Section 14.(c) shall also apply to any Loss
arising from Tenant's installation, operation, maintenance, repair or removal of
the Interconnection Equipment.

     12. Co-Location. Landlord acknowledges that Tenant's business to be
conducted in the Premises may require the installation in the Premises of
certain communications equipment by certain licensees and customers of Tenant to
permit such customers to interconnect with Tenant's equipment or to permit
Tenant to manage or operate such customers' equipment, or otherwise as may be
required pursuant to applicable Law. Notwithstanding any contrary provision
herein, Tenant shall not enter into any sublease, license agreement, co-location
agreement or similar agreement without first obtaining Landlord's written
consent, which shall not be unreasonably withheld.

     13. Assignment and Subletting.

          (a) Transfers. Except as provided in Section 13.(g), Tenant shall not,
without the prior written consent of Landlord, (1) assign, transfer, or encumber
this Lease or any estate or interest herein, whether directly or by operation of
law, (2) permit any other entity to become Tenant hereunder by merger,
consolidation, or other reorganization, (3) if Tenant is an entity other than a
corporation whose stock is publicly traded, permit the transfer of an ownership
interest in Tenant so as to result in a change in the current control of Tenant,
(4) sublet any portion of the Premises, (5) grant any license, concession, or
other right of occupancy of any portion of the Premises, or (6) permit the use
of the Premises by any parties other than Tenant (any of the events listed in
Section 13.(a)(l) through 13.(a)(6) being a "Transfer").

          (b) Consent Standards. Landlord shall not unreasonably withhold its
consent to any assignment or subletting of the Premises, provided that the
proposed transferee (1) is creditworthy, (2) has a good reputation in the
business community, (3) will use the Premises for the Permitted Use (thus,
excluding, without limitation, uses for credit processing and telemarketing) and
will not use the Premises in any manner that would conflict with any exclusive
use agreement or other similar agreement entered into by Landlord with any other
tenant of the Building (4) is not a governmental entity, or subdivision or
agency thereof, and (5) is not another occupant of the Building or person or
entity with whom Landlord is negotiating to lease space in the Building;
otherwise, Landlord may withhold its consent in its sole discretion.

          (c) Request for Consent. If Tenant requests Landlord's consent to a
Transfer, then Tenant shall provide Landlord with a written description of all
terms and conditions of the proposed Transfer, copies of the proposed
documentation, and the following information about the proposed transferee: name
and address; reasonably satisfactory information about its business and business
history; its proposed use of the Premises, banking, financial, and other credit
information, and general references sufficient to enable Landlord to determine
the proposed transferee's creditworthiness and character. Concurrently with
Tenant's notice of any request for consent to a Transfer, Tenant shall pay to
Landlord a fee of $750 to defray Landlord's expenses in reviewing such request,
and Tenant shall also reimburse Landlord immediately upon request for its
reasonable attorneys' fees incurred in connection with considering any request
for consent to a Transfer.

          (d) Conditions to Consent. If Landlord consents to a proposed
Transfer, then the proposed transferee shall deliver to Landlord a written
agreement whereby it expressly assumes Tenant's obligations hereunder; however,
any transferee of less than all of the space in the Premises shall be liable
only for obligations under this Lease that are properly allocable to the space
subject to the Transfer for the period of the Transfer. No Transfer shall
release Tenant from its obligations under this Lease, but rather Tenant and its

                                       10
<PAGE>

transferee shall be jointly and severally liable therefor. Landlord's consent to
any Transfer shall not waive Landlord's rights as to any subsequent Transfers.
If an Event of Default occurs while the Premises or any part thereof are subject
to a Transfer, then Landlord, in addition to its other remedies, may collect
directly from such transferee all rents becoming due to Tenant and apply such
rents against Rent. Tenant authorizes its transferees to make payments of rent
directly to Landlord upon receipt of notice from Landlord to do so. Tenant shall
pay for the cost of any demising walls or other improvements necessitated by a
proposed subletting or assignment.

          (e) Cancellation. Landlord may, within 30 days after submission of
Tenant's written request for Landlord's consent to an assignment or subletting
cancel this Lease as to the portion of the Premises proposed to be sublet or
assigned as of the date the proposed Transfer is to be effective, If Landlord
cancels this Lease as to any portion of the Premises, then this Lease shall
cease for such portion of the Premises and Tenant shall pay to Landlord all Rent
accrued through the cancellation date relating to the portion of the Premises
covered by the proposed Transfer. Thereafter, Landlord may lease such portion of
the Premises to the prospective transferee (or to any other person) without
liability to Tenant.

          (f) Additional Compensation. Tenant shall pay to Landlord, immediately
upon receipt thereof, the excess of (l) all compensation received by Tenant for
a Transfer less the costs reasonably incurred by Tenant with unaffiliated third
parties in connection with such Transfer (i.e., brokerage commissions, tenant
finish work, and the like) over (2) the Rent allocable to the portion of the
Premises covered thereby.

          (g) Permitted Transfers. Notwithstanding Section 13.(a), Tenant may
Transfer all or part of its interest in this Lease or all or part of the
Premises (a "Permitted Transfer") to the following types of entities (a
"Permitted Transferee") without the written consent of Landlord:

                   (1) an Affiliate of Tenant;

                   (2) any corporation, limited partnership, limited liability
       partnership, limited liability company or other business entity in which
       or with which Tenant, or its corporate successors or assigns, is merged
       or consolidated, in accordance with applicable statutory provisions
       governing merger and consolidation of business entities, so long as (D)
       Tenant's obligations hereunder are assumed by the entity surviving such
       merger or created by such consolidation; and (E) the Tangible Net Worth
       of the surviving or created entity is not less than the Tangible Net
       Worth of Tenant as of the date hereof; or

                   (3) any corporation, limited partnership, limited liability
       partnership, limited liability company or other business entity acquiring
       all or substantially all of Tenant's assets if such entity's Tangible Net
       Worth after such acquisition is not less than the Tangible Net Worth of
       Tenant as of the date hereof.

Tenant shall promptly notify Landlord of any such Permitted Transfer. Tenant
shall remain liable for the performance of all of the obligations of Tenant
hereunder, or if Tenant no longer exists because of a merger, consolidation, or
acquisition, the surviving or acquiring entity shall expressly assume in writing
the obligations of Tenant hereunder. Additionally, the Permitted Transferee
shall comply with all of the terms and conditions of this Lease, including the
Permitted Use, and the use of the Premises by the Permitted Transferee may not
violate any other agreements affecting the Premises, the Building, Landlord or
other tenants of the Building. At least 30 days after the effective date of any
Permitted Transfer, Tenant agrees to furnish Landlord with copies of the
instrument effecting any of the foregoing Transfers and documentation
establishing Tenant's satisfaction of the requirements set forth above
applicable to any such Transfer. The occurrence of a Permitted Transfer shall
not waive Landlord's rights as to any subsequent Transfers. "Tangible Net Worth"
means the excess of total assets over total liabilities, in each case as
determined in accordance with generally accepted accounting principles
consistently applied ("GAAP"), excluding, however, from the determination of
total assets all assets which would

                                       11
<PAGE>

be classified as intangible assets under GAAP including without limitation,
goodwill, licenses, patents, trademarks, trade names, copyrights, and
franchises. Any subsequent Transfer by a Permitted Transferee shall be subject
to Landlord's prior written consent (which Landlord may grant or deny in its
sole discretion).

     14. Insurance: Waivers: Subrogation; Indemnity.

          (a) Insurance. Tenant shall maintain throughout the Term the following
insurance policies: (1) commercial general liability insurance in amounts of
$3,000,000 per occurrence or such other amounts as Landlord may from time to
time reasonably require, insuring Tenant, Landlord, Landlord's agents and their
respective Affiliates against all liability for injury to or death of a person
or persons or damage to property arising from the use and occupancy of the
Premises and the installation, operation, maintenance, repair or removal of any
of Tenant's Equipment, Electrical Equipment, Lines, or Interconnection
Equipment, (2) insurance covering the full value of Tenant's property and
improvements, and other property (including property of others) in the Premises,
(3) contractual liability insurance sufficient to cover Tenant's indemnity
obligations hereunder (but only if such contractual liability insurance is not
already included in Tenant's commercial general liability insurance policy), (4)
worker's compensation insurance, containing a waiver of subrogation endorsement
acceptable to Landlord, and (5) business interruption insurance. Tenant's
insurance shall provide primary coverage to Landlord when any policy issued to
Landlord provides duplicate or similar coverage, and in such circumstance
Landlord's policy will be excess over Tenant's policy. Tenant shall furnish to
Landlord certificates of such insurance and such other evidence satisfactory to
Landlord of the maintenance of all insurance coverages required hereunder, and
Tenant shall obtain a written obligation on the part of each insurance company
to notify Landlord at least 30 days before cancellation or a material change of
any such insurance policies. All such insurance policies shall be in form, and
issued by companies, reasonably satisfactory to Landlord

          (b) Waiver of Negligence; No Subrogation. Landlord and Tenant each
waives any claim it might have against the other for any injury to or death of
any person or persons or damage to or theft, destruction, loss, or loss of use
of any property (a "Loss"), to the extent the same is insured against under any
insurance policy that covers the Building, the Premises, Landlord's or Tenant's
fixtures, personal property, leasehold improvements, or business, or, in the
case of Tenant's waiver, is required to be insured against under the terms
hereof; regardless of whether the negligence of the other party caused such
Loss; however, Landlord's waiver shall not include any deductible amounts on
insurance policies carried by Landlord. Each party shall cause its insurance
carrier to endorse all applicable policies waiving the carrier's rights of
recovery under subrogation or otherwise against the other party.

          (c) Indemnity. Subject to Section 14(b), Tenant shall defend,
indemnify, and hold harmless Landlord and its representatives and agents from
and against all claims, demands, liabilities, causes of action, suits,
judgments, damages, and expenses (including attorneys' fees) arising from (1)
any Loss arising from any occurrence on the Premises (other than any Loss
arising out of a breach of Tenant's obligations under Section 28.(t), which
shall be subject to the indemnity in such section) or arising out of the
installation, operation, maintenance, repair or removal of any of Tenant's
Equipment, Electrical Equipment, Lines or Interconnection Equipment, or (2)
Tenant's failure to perform its obligations under this Lease, even though caused
or alleged to he caused by the negligence or fault of Landlord or its agents
(other than a Loss arising from the sole or gross negligence of Landlord or its
agents), and even though any such claim, cause of action, or suit is based upon
or alleged to be based upon the strict liability of Landlord or its agents. This
indemnity is intended to indemnify Landlord and its agents against the
consequences of their own negligence when Landlord or its agents are jointly,
comparatively, contributively, or concurrently negligent with Tenant. This
indemnity provision shall survive termination or expiration of this Lease. if
any proceeding is filed for which indemnity is required hereunder, Tenant
agrees, upon request therefor, to defend the indemnified party in such
proceeding at its sole cost utilizing counsel satisfactory to the indemnified
party.

                                       12
<PAGE>

     15. Subordination; Attornment; Notice to Landlord's Mortgagee.

          (a) Subordination. This Lease shall be subordinate to any deed of
trust, mortgage, or other security instrument, or any ground lease, master
lease, or primary lease, that now or hereafter covers all or any part of the
Premises (the mortgagee under any such mortgage or the lessor under any such
lease is referred to herein as a "Landlord's Mortgagee"). Any Landlord's
Mortgagee may elect, at any time, unilaterally, to make this Lease superior to
its mortgage, ground lease, or other interest in the Premises by so notifying
Tenant in writing.

          (b) Attornment. Tenant shall attorn to any party succeeding to
Landlord's interest in the Premises, whether by purchase, foreclosure, deed in
lieu of foreclosure, power of sale, termination of lease, or otherwise, upon
such party's request, and shall execute such agreements confining such
attornment as such party may reasonably request

          (c) Notice to Landlord's Mortgagee. Tenant shall not seek to enforce
any remedy it may have for any default on the part of Landlord without first
giving written notice by certified mail, return receipt requested, specifying
the default in reasonable detail, to any Landlord's Mortgagee whose address has
been given to Tenant, and affording such Landlord's Mortgagee a reasonable
opportunity to perform Landlord's obligations hereunder.

          (d) Landlord's Mortgagee's Protection Provisions. If Landlord's
Mortgagee shall succeed to the interest of Landlord under this Lease, Landlord's
Mortgagee shall not be: (1) liable for any act or omission of any prior lessor
(including Landlord); (2) bound by any rent or additional rent or advance rent
which Tenant might have paid for more than the current month to any prior lessor
(including Landlord), and all such rent shall remain due and owing
notwithstanding such advance payment; (3) bound by any security or advance
rental deposit made by Tenant which is not delivered or paid over to Landlord's
Mortgagee and with respect to which Tenant shall look solely to Landlord for
refund or reimbursement; (4) bound by any termination, amendment or modification
of this Lease made without Landlord's Mortgagee's consent and written approval,
except for those terminations, amendments and modifications permitted to be made
by Landlord without Landlord's Mortgagee's consent pursuant to the terms of the
loan documents between Landlord and Landlord's Mortgagee; (5) subject to the
defenses which Tenant might have against any prior lessor (including Landlord);
and (6) subject to the offsets which Tenant might have against any prior lessor
(including Landlord) except for those offset rights which (7) are expressly
provided in this Lease, (8) relate to periods of time following the acquisition
of the Building by Landlord's Mortgagee, and (9) Tenant has provided written
notice to Landlord's Mortgagee and provided Landlord's Mortgagee a reasonable
opportunity to cure the event giving rise to such offset event. Landlord's
Mortgagee shall have no liability or responsibility under or pursuant to the
terms of this Lease or otherwise after it ceases to own an interest in the
Building. Nothing in this Lease shall be construed to require Landlord's
Mortgagee to see to the application of the proceeds of any loan, and Tenant's
agreements set forth herein shall not be impaired on account of any modification
of the documents evidencing and securing any loan.

     16. Rules and Regulations. Tenant shall comply with the rules and
regulations of the Building which are attached hereto as Exhibit C. Landlord
may, from time to time, change such rules and regulations for the safety, care,
or cleanliness of the Building and related facilities, provided that such
changes are applicable to all tenants of the Building and will not unreasonably
interfere with Tenant's use of the Premises. Tenant shall be responsible for the
compliance with such rules and regulations by each Tenant Party.

     17. Condemnation.

          (a) Total Taking. If the entire Building or Premises are taken by
right of eminent domain or conveyed in lieu thereof (a "Taking"), this Lease
shall terminate as of the date of the Taking.

                                       13
<PAGE>

          (b) Partial Taking - Tenant's Rights. If any part of the Building
becomes subject to a Taking and such Taking will prevent Tenant from conducting
its business in the Premises in a manner reasonably comparable to that conducted
immediately before such Taking for a period of more than 180 days, then Tenant
may terminate this Lease as of the date of such Taking by giving written notice
to Landlord within 30 days after the Taking and Rent shall be apportioned as of
the date of such Taking. If Tenant does not terminate this Lease then Rent shall
be abated on a reasonable basis as to that portion of the Premises rendered
untenantable by the Taking.

          (c) Partial Taking - Landlord's Rights. if any material portion, but
less than all, of the Building becomes subject to a Taking or if Landlord is
required to pay any of the proceeds received for a Taking to a Landlord's
Mortgagee, then Landlord may terminate this Lease by delivering written notice
thereof to Tenant within 30 days after such Taking and Rent shall be apportioned
as of the date of such Taking. if Landlord does not so terminate this Lease,
then this Lease will continue, but if any portion of the Premises has been
taken, Rent shall abate as provided in the last sentence of Section 17.(b).

          (d) Award. If any Taking occurs, then Landlord shall receive the
entire award or other compensation for the land on which the Building is
situated, the Building, and other improvements taken, and Tenant may separately
pursue a claim (to the extent it will not reduce Landlord's award) against the
condemnor for the value of Tenant's personal property which Tenant is entitled
to remove under this Lease, moving costs, loss of business, and other claims it
may have.

     18. Fire or Other Casualty.

          (a) Repair Estimate. If the Premises or the Building are damaged by
fire or other casualty (a "Casualty"), Landlord shall, within 90 days after such
Casualty, deliver to Tenant a good faith estimate (the "Damage Notice") of the
time needed to repair the damage caused by such Casualty.

          (b) Landlord's and Tenant's Rights. If a material portion of the
Premises or the Building is damaged by Casualty such that Tenant is prevented
from conducting its business in the Premises in a manner reasonably comparable
to that conducted immediately before such Casualty and Landlord estimates that
the damage caused thereby cannot be repaired within 270 days after the Casualty,
then Tenant may terminate this Lease by delivering written notice to Landlord of
its election to terminate within 30 days after the Damage Notice has been
delivered to Tenant if Tenant does not so timely terminate this Lease, then
(subject to Section 18.(c)) Landlord shall repair the Building or the Premises,
as the case may be, as provided below, and Rent for the portion of the Premises
rendered untenantable by the damage shall be abated on a reasonable basis from
the date of damage until the completion of the repair, unless a Tenant Party
caused such damage, in which case, Tenant shall continue to pay Rent without
abatement

          (c) Landlord's Rights. If a Casualty damages a material portion of the
Building, and Landlord makes a good faith determination that restoring the
Premises would be uneconomical, or if Landlord is required to pay any insurance
proceeds arising out of the Casualty to a Landlord's Mortgagee, then Landlord
may terminate this Lease by giving written notice of its election to terminate
within 30 days after the Damage Notice has been delivered to Tenant, and shall
be abated as of the date of the Casualty

          (d) Repair Obligation. If neither party elects to terminate this Lease
following a Casualty, then Landlord shall, within a reasonable time after such
Casualty, begin to repair the Building and the Premises and shall proceed with
reasonable diligence to restore the Building and Premises to substantially the
same condition as they existed immediately before such Casualty; however,
Landlord shall not be required to repair or replace any of the furniture,
equipment fixtures, and other improvements which may have been placed by, or at
the request of, Tenant or other occupants in the Building or the Premises, and
Landlord's obligation to repair

                                       14
<PAGE>

or restore the Building or Premises shall be limited to the extent of the
insurance proceeds actually received by Landlord for the Casualty in question.

     19. Personal Property Taxes. Tenant shall be liable for all taxes levied or
assessed against personal property, furniture, or fixtures (including Tenant's
Equipment, Electrical Equipment, Lines and the Interconnection Equipment) placed
by Tenant in the Premises or in or on the Building or Project. If any taxes for
which Tenant is liable are levied or assessed against Landlord or Landlord's
property and Landlord elects to pay the same, or if the assessed value of
Landlord's property is increased by inclusion of such personal property,
furniture or fixtures and Landlord elects to pay the taxes based on such
increase, then Tenant shall pay to Landlord, upon demand, the part of such taxes
for which Tenant is primarily liable hereunder; however, Landlord shall not pay
such amount if Tenant notifies Landlord that it will contest the validity or
amount of such taxes before Landlord makes such payment, and thereafter
diligently proceeds with such contest in accordance with law and if the
non-payment thereof does not pose a threat of loss or seizure of the Building or
interest of Landlord therein or impose any fee or penalty against Landlord.

     20. Events of Default. Each of the following occurrences shall be an "Event
of Default":

          (a) Tenant's failure to pay Rent within five days after Landlord has
delivered notice to Tenant that the same is due; however, an Event of Default
shall occur hereunder without any obligation of Landlord to give any notice if
Landlord has given Tenant written notice under this Section 20.(a) on more than
one occasion during the twelve (12) month interval preceding such failure by
Tenant;

          (b) Intentionally deleted.

          (c) Tenant fails to comply with the Permitted Use set forth herein and
the continuance of such failure for a period of five (5) days after Landlord has
delivered to Tenant written notice thereof;

          (d) Tenant fails to provide any estoppel certificate within the time
period required under Section 28(e) and such failure shall continue for five
days after written notice thereof from Landlord to Tenant;

             (e) Tenant's failure to perform, comply with, or observe any other
agreement or obligation of Tenant under this Lease and the continuance of such
failure for a period of more than 30 days after Landlord has delivered to Tenant
written notice thereof; and

             (f) The filing of a petition by or against Tenant (the term
"Tenant" shall include, for the purpose of this Section 20.(f), any guarantor of
Tenant's obligations hereunder) (1) in any bankruptcy or other insolvency
proceeding; (2) seeking any relief under any state or federal debtor relief law;
(3) for the appointment of a liquidator or receiver for all or substantially all
of Tenant's property or for Tenant's interest in this Lease; or (4) for the
reorganization or modification of Tenant's capital structure; however, if such a
petition is filed against Tenant, then such filing shall not be an Event of
Default unless Tenant fails to have the proceedings initiated by such petition
dismissed within 90 days after the filing thereof.

     21. Remedies. Upon any Event of Default, Landlord may, in addition to all
other rights and remedies afforded Landlord hereunder or by law or equity, take
any of the following actions:

            (a) Terminate this Lease by giving Tenant written notice thereof; in
which event Tenant shall pay to Landlord the sum of(1) all Rent accrued
hereunder through the date of termination, (2) all amounts due under Section
22.(a), and (3) an amount equal to (F) the total Rent that Tenant would have
been required to pay for the remainder of the Term discounted to present value
at a per annum rate equal to the "Prime Rate" as

                                       15
<PAGE>

published on the date this Lease is terminated by The Wall Street Journal,
Southwest Edition, in its listing of "Money Rates", minus (G) the then present
fair rental value of the Premises for such period, similarly discounted;

          (b) Terminate Tenant's right to possess the Premises without
terminating this Lease by giving written notice thereof to Tenant, in which
event Tenant shall pay to Landlord (1) all Rent and other amounts accrued
hereunder to the date of termination of possession, (2) all amounts due from
time to time under Section 22.(a), and (3) all Rent and other net sums required
hereunder to be paid by Tenant during the remainder of the Term, diminished by
any net sums thereafter received by Landlord through reletting the Premises
during such period, after deducting all costs incurred by Landlord in reletting
the Premises. Landlord shall use reasonable efforts to relet the Premises on
such terms as Landlord in its sole discretion may determine (including a term
different from the Term, rental concessions, and alterations to, and improvement
of, the Premises); however, Landlord shall not be obligated to relet the
Premises before leasing other portions of the Building. Landlord shall not be
liable for, nor shall Tenant's obligations hereunder be diminished because of;
Landlord's failure to relet the Premises or to collect rent due for such
reletting. Tenant shall not be entitled to the excess of any consideration
obtained by reletting over the Rent due hereunder. Reentry by Landlord in the
Premises shall not affect Tenant's obligations hereunder for the unexpired Term;
rather, Landlord may from time to time, bring an action against Tenant to
collect amounts due by Tenant, without the necessity of Landlord's waiting until
the expiration of the Term. Unless Landlord delivers written notice to Tenant
expressly stating that it has elected to terminate this Lease, all actions taken
by Landlord to dispossess or exclude Tenant from the Premises shall be deemed to
be taken under this Section 21.(b). If Landlord elects to proceed under this
Section 21.(b), it may at any time elect to terminate this Lease under Section
21.(a); or

          (c) Additionally, without notice, Landlord may alter locks or other
security devices at the Premises to deprive Tenant of access thereto, and
Landlord shall not be required to provide a new key or right of access to
Tenant.

       22.   Payment by Tenant: Non-Waiver.

          (a) Payment by Tenant. Upon any Event of Default, Tenant shall pay to
Landlord all costs incurred by Landlord (including court costs and reasonable
attorneys' fees and expenses) in (1) obtaining possession of the Premises, (2)
removing and storing Tenant's or any other occupant's property, (3) repairing,
restoring, altering, remodeling, or otherwise putting the Premises into
condition acceptable to a new tenant, (4) if Tenant is dispossessed of the
Premises and this Lease is not terminated, reletting all or any part of the
Premises (including brokerage commissions, cost of tenant finish work and
other costs incidental to such reletting), (5) performing Tenant's obligations
which Tenant failed to perform, and (6) enforcing, or advising Landlord of; its
rights, remedies, and recourses arising out of the Event of Default. To the full
extent permitted by law, Landlord and Tenant agree the federal and state courts
of the state in which the Premises are located shall have exclusive jurisdiction
over any matter relating to or arising from this Lease and the parties' rights
and obligations under this Lease.

          (b) No Waiver. Landlord's acceptance of Rent following an Event of
Default shall not waive Landlord's rights regarding such Event of Default. No
waiver by Landlord of any violation or breach of any of the terms contained
herein shall waive Landlord's rights regarding any future violation of such
term. Landlord's acceptance of any partial payment of Rent shall not waive
Landlord's rights with regard to the remaining portion of the Rent that is due,
regardless of any endorsement or other statement on any instrument delivered in
payment of Rent or any writing delivered in connection therewith; accordingly,
Landlord's acceptance of a partial payment of Rent shall not constitute an
accord and satisfaction of the full amount of the Rent that is due.

     23. Intentionally deleted.

                                       16
<PAGE>

     24. Surrender of Premises. No act by Landlord shall be deemed an acceptance
of a surrender of the Premises, and no agreement to accept a surrender of the
Premises shall be valid unless it is in writing and signed by Landlord. At the
expiration or termination of this Lease, Tenant shall deliver to Landlord the
Premises with all improvements located therein in good repair and condition,
free of Hazardous Materials placed on the Premises during the Term, broom-clean,
reasonable wear and tear (and condemnation and Casualty damage not caused by
Tenant, as to which Sections 17 and 18 shall control) excepted, and shall
deliver to Landlord all keys to the Premises. Provided that Tenant has performed
all of its obligations hereunder, Tenant may remove all unattached trade
fixtures, furniture, and personal property placed in the Premises or elsewhere
in the Building by Tenant (but Tenant may not remove any such item which was
paid for, in whole or in part, by Landlord or any wiring or cabling unless
Landlord requires such removal). Additionally, at Landlord's option, Tenant
shall remove such alterations, additions, improvements, trade fixtures, personal
property, equipment, wiring, conduits, cabling, and furniture (including
Tenant's Equipment, Electrical Equipment, Lines and the Interconnection
Equipment) as Landlord may request; however, Tenant shall not be required to
remove any addition or improvement to the Premises or the Project if Landlord
has specifically agreed in writing that the improvement or addition in question
need not be removed. Tenant shall repair all damage caused by such removal. All
items not so removed shall, at Landlord's option, be deemed to have been
abandoned by Tenant and may be appropriated, sold, stored, destroyed, or
otherwise disposed of by Landlord without notice to Tenant and without any
obligation to account for such items; any such disposition shall not be
considered a strict foreclosure or other exercise of Landlord's rights in
respect of the security interest granted under Section 23. The provisions of
this Section 24 shall survive the end of the Term.

     25. Holding Over. If Tenant fails to vacate the Premises at the end of the
Term, then Tenant shall be a tenant at will and, in addition to all other
damages and remedies to which Landlord may be entitled for such holding over,
Tenant shall pay; in addition to the other Rent, a daily Basic Rent equal to the
greater of (a) 150% of the daily Basic Rent payable during the last month of the
Term, or (b) 125% of the prevailing rental rate in the Building for similar
space. The provisions of this Section 25 shall not be deemed to limit or
constitute a waiver of any other rights or remedies of Landlord provided herein
or at law. If Tenant fails to surrender the Premises upon the termination or
expiration of this Lease, in addition to any other liabilities to Landlord
accruing therefrom, Tenant shall protect, defend, indemnify and hold Landlord
harmless from all loss, costs (including reasonable attorneys' fees) and
liability resulting from such failure, including, without limiting the
generality of the foregoing, any claims made by any succeeding tenant founded
upon such failure to surrender, and any lost profits to Landlord resulting
therefrom.

     26. Certain Rights Reserved by Landlord. Provided that the exercise of such
rights does not unreasonably interfere with Tenant's occupancy of the Premises,
Landlord shall have the following rights:

          (a) To decorate and to make inspections, repairs, alterations,
additions, changes, or improvements, whether structural or otherwise, in and
about the Project, or any part thereof; to enter upon the Premises (after giving
Tenant reasonable notice thereof, which may be oral notice, except in cases of
real or apparent emergency, in which case no notice shall be required) and,
during the continuance of any such work, to temporarily close doors, entryways,
public space, and corridors in the Building; to interrupt or temporarily suspend
Building services and facilities; to change the name of the Building, and to
change the arrangement and location of entrances or passageways, doors, and
doorways, corridors, elevators, stairs, restrooms, or other public parts of the
Building;

          (b) To take such reasonable measures as Landlord deems advisable for
the security of the Project and Building occupants; evacuating the Building for
cause, suspected cause, or for drill purposes; temporarily denying access to the
Building, and closing the Building after normal business hours and on Sundays

                                       17
<PAGE>

and holidays, subject, however, to Tenant's right to enter when the Building is
closed after normal business hours under such reasonable regulations as Landlord
may prescribe from time to time; and

          (c) To enter the Premises at reasonable hours, to show the Premises to
prospective purchasers, lenders, or, during the last six months of the Term,
tenants.

     27. Substitution Space. Intentionally deleted.

     28. Miscellaneous.

          (a) Landlord Transfer. Landlord may transfer any portion of the
Building and any of its rights under this Lease. If Landlord assigns its rights
under this Lease, then Landlord shall thereby be released from any further
obligations hereunder arising after the date of transfer, provided that the
assignee assumes Landlord's obligations hereunder in writing.

          (b) Landlord's Liability. The liability of Landlord to Tenant for any
default by Landlord under the terms of this Lease shall be limited to Tenant's
actual direct, but not consequential, damages therefor and shall be recoverable
only from the interest of Landlord in the Building, and Landlord shall not be
personally liable for any deficiency. This Section shall not limit any remedies
which Tenant may have for Landlord's defaults which do not involve the personal
liability of Landlord.

          (c) Force Majeure. Other than for Tenant's obligations under this
Lease that can be performed by the payment of money (e.g., payment of Rent and
maintenance of insurance), whenever a period of time is herein prescribed for
action to be taken by either party hereto, such party shall not be liable or
responsible for, and there shall be excluded from the computation of any such
period of time, any delays due to strikes, riots, acts of God, shortages of
labor or materials, war, governmental laws, regulations, or restrictions, or any
other causes of any kind whatsoever which are beyond the control of such party

          (d) Brokerage. Neither Landlord nor Tenant has dealt with any broker
or agent in connection with the negotiation or execution of this Lease, other
than Duggan Realty Advisors L.L.C. and Mohr Partners, whose commission shall be
paid by the Landlord. Tenant and Landlord shall each indemnify the other against
all costs, expenses, attorneys' fees, and other liability for commissions or
other compensation claimed by any broker or agent claiming the same by, through,
or under the indemnifying party.

          (e) Estoppel Certificates. From time to time, Tenant shall finish to
any party designated by Landlord, within ten days after Landlord has made a
request therefor, a certificate signed by Tenant confirming and containing such
factual certifications and representations as to this Lease as Landlord may
reasonably request. Unless otherwise required by Landlord's Mortgagee or a
prospective purchaser or mortgagee of the Building, the initial form of estoppel
certificate to be signed by Tenant is attached hereto as Exhibit F.

          (f) Notices. All notices and other communications given pursuant to
this Lease shall be in writing and shall be (1) mailed by first class, United
States Mail, postage prepaid, certified, with return receipt requested, and
addressed to the parties hereto at the address specified in the Basic Lease
Information, (2) hand delivered to the intended address, (3) sent by a
nationally recognized overnight courier service, or (4) sent by facsimile
transmission during normal business hours followed by a confirmatory letter sent
in another manner permitted hereunder. All notices shall be effective upon
delivery to the address of the addressee. The parties hereto may change their
addresses by giving notice thereof to the other in conformity with this
provision.

          (g) Separabilitv. If any clause or provision of this Lease is illegal,
invalid, or unenforceable under present or future laws, then the remainder of
this Lease shall not be affected thereby and in

                                       18
<PAGE>

lieu of such clause or provision, there shall be added as a part of this Lease a
clause or provisions similar in terms to such illegal, invalid, or unenforceable
clause or provision as may be possible and be legal, valid, and enforceable.

          (h) Amendments; and Binding Effect. This Lease may not be amended
except by Instrument in writing signed by Landlord and Tenant. No provision of
this Lease shall be deemed to have been waived by Landlord unless such waiver is
in writing signed by Landlord, and no custom or practice which may evolve
between the parties in the administration of the terms hereof shall waive or
diminish the right of Landlord to insist upon the performance by Tenant in
strict accordance with the terms hereof. The terms and conditions contained in
this Lease shall inure to the benefit of and be binding upon the parties hereto,
and upon their respective successors in interest and legal representatives,
except as otherwise herein expressly provided. This Lease is for the sole
benefit of Landlord and Tenant, and, other than Landlord's Mortgagee, no third
party shall be deemed a third party beneficiary hereof.

          (i) Quiet Enjoyment. Provided Tenant has performed all of its
obligations hereunder, Tenant shall peaceably and quietly hold and enjoy the
Premises for the Term, without hindrance from Landlord or any party claiming by,
through, or under Landlord, but not otherwise, subject to the terms and
conditions of this Lease.

          (j) No Merger. There shall be no merger of the leasehold estate hereby
created with the fee estate in the Premises or any part thereof if the same
person acquires or holds, directly or indirectly, this Lease or any interest in
this Lease and the fee estate in the leasehold Premises or any interest in such
fee estate.

          (k) No Offer. The submission of this Lease to Tenant shall not be
construed as an offer, and Tenant shall not have any rights under this Lease
unless Landlord executes a copy of this Lease and delivers it to Tenant.

          (l) Entire Agreement. This Lease constitutes the entire agreement
between Landlord and Tenant regarding the subject matter hereof and supersedes
all oral statements and prior writings relating thereto. Except for those set
forth in this Lease, no representations, warranties, or agreements have been
made by Landlord or Tenant to the other with respect to this Lease or the
obligations of Landlord or Tenant in connection therewith. The normal rule of
construction that any ambiguities be resolved against the drafting party shall
not apply to the interpretation of this Lease or any exhibits or amendments
hereto.

          (m) Waiver of Jury Trial. To the maximum extent permitted by law,
Landlord and Tenant each waive right to trial by jury in any litigation arising
out of or with respect to this Lease.

          (n) Governing Law. This Lease shall be governed by and construed in
accordance with the laws of the State in which the Premises are located.

          (o) Joint and Several Liability. If Tenant is comprised of more than
one party, each such party shall be jointly and severally liable for Tenant's
obligations under this Lease.

          (p) Financial Reports. Within 15 days after Landlord's request, Tenant
will finish Tenant's most recent audited financial statements (including any
notes to them) to Landlord, or, if no such audited statements have been
prepared, such other financial statements (and notes to them) as may have been
prepared by an independent certified public accountant or, failing those,
Tenant's internally prepared financial statements. If Tenant is a publicly
traded corporation, Tenant may satisfy its obligations hereunder by providing to
Landlord Tenant's most recent annual and quarterly reports. Tenant will discuss
its financial statements with Landlord and will give Landlord access to Tenant's
books and records in order to enable Landlord to verify the financial

                                       19
<PAGE>

statements. Landlord will not disclose any aspect of Tenant's financial
statements that Tenant designates to Landlord as confidential except (1) to
Landlord's Mortgagee or prospective purchasers of the Building, (2) in
litigation between Landlord and Tenant, and (3) if required by court order.
Tenant shall not be required to deliver the financial statements required under
this Section 28.(p) more than once in any 12-month period unless requested by
Landlord's Mortgagee or a prospective buyer or lender of the Building or an
Event of Default occurs.

          (q) Landlord's Fees. Whenever Tenant requests Landlord to take any
action not required of it hereunder or give any consent required or permitted
under this Lease, Tenant will reimburse Landlord for Landlord's reasonable,
out-of-pocket costs payable to third parties and incurred by Landlord in
reviewing the proposed action or consent, including without attorneys',
engineers' or architects' fees, within ten days after Landlord's delivery to
Tenant of a statement of such costs. Tenant will be obligated to make such
reimbursement without regard to whether Landlord consents to any such proposed
action.

          (r) Telecommunications. Tenant and its telecommunications companies,
including but not limited to local exchange telecommunications companies and
alternative access vendor services companies shall have no right of access to
and within the Building, for the installation and operation of
telecommunications systems including but not limited to voice, video, data, and
any other telecommunications services provided over wire, fiber optic,
microwave, wireless, and any other transmission systems, for part or all of
Tenant's telecommunications within the Building and from the Building to any
other location without Landlord's prior written consent, which shall not be
unreasonably withheld, conditioned or delayed.

          (s) Confidentiality. Tenant acknowledges that the terms and conditions
of this Lease are to remain confidential for Landlord's benefit, and may not be
disclosed by Tenant to anyone, by any manner or means, directly or indirectly,
without Landlord's prior written consent The consent by Landlord to any
disclosures shall not be deemed to be a waiver on the part of Landlord of any
prohibition against any future disclosure.

          (t) Hazardous Materials. The term "Hazardous Materials" means any
substance, material, or waste which is now or herein classified or considered to
be hazardous, toxic, or dangerous under any Law relating to pollution or the
protection or regulation of human health, natural resources or the environment,
or poses or threatens to pose a hazard to the health or safety of persons on the
Premises or in the Building. Tenant shall not use, generate, store, or dispose
of, or permit the use, generation, storage or disposal of Hazardous Materials on
or about the Premises or the Building except in a manner and quantity necessary
for the ordinary performance of Tenant's business, and then in compliance with
all Laws. If Tenant breaches its obligations under this Section 28.(t), Landlord
may immediately take any and all action reasonably appropriate to remedy the
same, including taking all appropriate action to clean up or remediate any
contamination resulting from Tenant's use, generation, storage or disposal of
Hazardous Materials. Tenant shall defend, indemnify, and hold harmless Landlord
and its representatives and agents from and against any and all claims, demands,
liabilities, causes of action, suits, judgments, damages and expenses (including
reasonable attorneys' fees and cost of clean up and remediation) arising from
Tenant's failure to comply with the provisions of this Section 28.(t). This
indemnity provision shall survive termination or expiration of the Lease.

                                       20
<PAGE>

          (u) List of Exhibits. All exhibits and attachments attached hereto are
incorporated herein by this reference.

Exhibit A-1    Outline of Premises
Exhibit A-2    Area for Location of Generator
Exhibit A-3    Area for Location of Cooling Equipment
Exhibit B -    Legal Description of Building
Exhibit C -    Building Rules and Regulations
Exhibit D -    Tenant Finish-Work
Exhibit E -    Amendment No. 1
Exhibit F -    Form of Tenant Estoppel Certificate
Exhibit H -    Renewal Options
Exhibit I -    Rent Abatement Provisions

     29. Other Provisions. None.

                                       21
<PAGE>

LANDLORD AND TENANT EXPRESSLY DISCLAIM ANY IMPLIED WARRANTY THAT THE PREMISES
ARE SUITABLE FOR TENANT'S INTENDED COMMERCIAL PURPOSE, AND TENANT'S OBLIGATION
TO PAY RENT HEREUNDER IS NOT DEPENDENT UPON THE CONDITION OF THE PREMISES OR THE
PERFORMANCE BY LANDLORD OF ITS OBLIGATIONS HEREUNDER, AND, EXCEPT AS OTHERWISE
EXPRESSLY PROVIDED HEREIN, TENANT SHALL CONTINUE TO PAY THE RENT, WITHOUT
ABATEMENT, SETOFF OR DEDUCTION, NOTWITHSTANDING ANY BREACH BY LANDLORD OF ITS
DUTIES OR OBLIGATIONS HEREUNDER, WHETHER EXPRESS OR IMPLIED.

     Dated as of the date first above written.

LANDLORD:                      DENVER FDS, L.P., a Texas limited partnership
                               By: FDS Realty Partners, L.L.C., a Texas limited
                               liability company, as general partner

                               By: /s/ JAMES F. DUGGAN
                               Name: James F. Duggan
                               Title: Manager

TENANT:                        ADVANCED TELECOMMUNICATIONS, INC., a Delaware
                               Corporation

                               By: /s/ SATISH TIWARI
                               Name:Satish Tiwari
                               Title: Vice President

                                       22
<PAGE>

                                  EXHIBIT A - 1

                              [OUTLINE OF PREMISES]

                            [IMAGE: MAP OF PREMISES]

DENVER FDS BUILDING
1500 CHAMPA STREET
BASEMENT FLOOR PLAN
NOVEMBER 6 1999

                                       A-1
<PAGE>

                                  EXHIBIT A - 2

                        [AREA FOR LOCATION OF GENERATOR]

                  [IMAGE: MAP OF SECOND AND THIRD FLOOR ROOF]

                                      A-2
<PAGE>

                                  EXHIBIT A - 3

                     [AREA FOR LOCATION OF COOLING EQUIPMENT]

                        [IMAGE: MAP OF SECOND FLOOR ROOF]

                                                            DENVER FDS BUILDING
                                                            1500 CHAMPA BUILDING
                                                            THIRD FLOOR PLAN

                                      A-3
<PAGE>

                                    EXHIBIT B

                        [LEGAL DESCRIPTION OF BUILDING]

PARCEL 1:

Lots 5 through 10, inclusive,

Block 130,

East Denver

City and County of Denver,

State of Colorado

PARCEL 2:

Lots II through 16, inclusive,

Block 130,

East Denver,

City and County of Denver,

State of Colorado

                                      B-1
<PAGE>

                                    EXHIBIT C

                         BUILDING RULES AND REGULATIONS

     The following rules and regulations shall apply to the Premises, the
Building the parking garage associated therewith, and the appurtenances thereto:

     1. Sidewalks, doorways, vestibules, halls, stairways, and other similar
areas shall not be obstructed by tenants or used by any tenant for purposes
other than ingress and egress to and from their respective leased premises and
for going from one to another part of the Building.

     2. Plumbing fixtures and appliances shall be used only for the purposes for
which designed, and no sweepings, rubbish, rags or other unsuitable material
shall be thrown or deposited therein. Damage resulting to any such fixtures or
appliances from misuse by a tenant or its agents, employees or invitees, shall
be paid by such tenant.

     3. No signs, advertisements or notices shall be painted or affixed on or to
any windows or doors or other part of the Building without the prior written
consent of Landlord. No nails, hooks or screws shall be driven or inserted in
any part of the Building except by Building maintenance personnel. No curtains
or other window treatments shall be placed between the glass and the Building
standard window treatments.

     4. Landlord shall provide and maintain an alphabetical directory for all
tenants in the main lobby of the Building.

     5. Landlord shall provide all door locks in each tenant's leased premises,
at the cost of such tenant, and no tenant shall place any additional door locks
in its leased premises without Landlord's prior written consent Landlord shall
furnish to each tenant a reasonable number of keys to such tenant's leased
premises, at such tenant's cost, and no tenant shall make a duplicate thereof.

     6. Movement in or out of the Building of furniture or other equipment, or
dispatch or receipt by tenants of any bulky material, merchandise or materials
which require use of elevators or stairways, or movement through the Building
entrances or lobby shall be conducted under Landlord's supervision at such times
and in such a manner as Landlord may reasonably require. Each tenant assumes all
risks of and shall be liable for all damage to articles moved and injury to
persons or public engaged or not engaged in such movement, including equipment,
property and personnel of Landlord if damaged or injured as a result of acts in
connection with carrying out this service for such tenant.

     7. Landlord may prescribe weight limitations and determine the locations
for safes and other heavy equipment or items, which shall in all cases be placed
in the Building so as to distribute weight in a manner acceptable to Landlord
which may include the use of such supporting devices as Landlord may require.
All damages to the Building caused by the installation or removal of any
property of a tenant, or done by a tenant's property while in the Building,
shall be repaired at the expense of such tenant.

     8. Corridor doors, when not in use, shall be kept closed. Nothing shall be
swept or thrown into the corridors, halls, elevator shafts or stairways. No
birds or animals shall be brought into or kept in, on or about any tenant's
leased premises. No portion of any tenant's leased premises shall at any time be
used or occupied as sleeping or lodging quarters.

                                   C-1
<PAGE>

     9. Tenant shall cooperate with Landlord's employees in keeping its leased
premises neat and clean. Without Landlord's prior written consent, Tenant shall
not employ any person for the purpose of such cleaning other than the Building's
cleaning and maintenance personnel.

     10. To ensure orderly operation of the Building, no ice, mineral or other
water, towels, newspapers, etc. shall be delivered to any leased area except by
persons approved by Landlord.

     11. Tenant shall not make or permit any vibration or improper,
objectionable or unpleasant noises or odors in the Building or otherwise
interfere in any way with other tenants or persons having business with them.

     12. No machinery of any kind (other than normal office equipment) shall be
operated by any tenant on its leased area without Landlord's prior written
consent, nor shall any tenant use or keep in the Building any flammable or
explosive fluid or substance.

     13. Landlord will not be responsible for lost or stolen personal property,
money or jewelry from tenants leased premises or public or common areas
regardless of whether such loss occurs when the area is locked against entry or
not.

     14. No vending or dispensing machines of any kind may be maintained in any
leased premises without the prior written permission of Landlord.

     15. Tenant shall not conduct any activity on or about the Premises or
Building which will draw pickets, demonstrators, or the like.

     16. All vehicles are to be currently licensed, in good operating condition,
parked for business purposes having to do with Tenant's business operated in
the Premises, parked within designated parking spaces, one vehicle to each
space. No vehicle shall be parked as a "billboard" vehicle or with for-sale
signs in the parking lot. Any vehicle parked improperly may be towed away.
Tenant, Tenant's agents, employees, vendors and customers who do not operate
or park their vehicles as required shall subject the vehicle to being towed
at the expense of the owner or driver. Landlord may place a "boot" on the
vehicle to immobilize it and may levy a charge of $50.00 to remove the
"boot." Tenant shall indemnify hold and save harmless Landlord of any
liability arising from the towing or booting of any vehicles belonging to a
Tenant Party.

     17. No tenant may enter into phone rooms, electrical rooms, mechanical
rooms, or other service areas of the Building unless accompanied by Landlord or
the Building manager.

                                       C-2
<PAGE>

                                    EXHIBIT D

                               TENANT FlNISH-WORK
                           (Tenant Performs the Work)

     1. Except as set forth in this Exhibit, Tenant accepts the Premises in
their "AS-IS" condition on the date that this Lease is entered into, and
Landlord shall have no obligation to perform any work therein (including without
limitation, demolition of any improvements existing therein or construction of
any tenant finish-work or other improvements therein), and shall not be
obligated to reimburse Tenant or provide an allowance for any costs related to
the demolition or construction of improvements therein.

     2. Prior to commencing construction, Tenant shall provide to Landlord for
its approval final working drawings, prepared by an architect that has been
approved in writing by Landlord (which approval shall not be unreasonably
withheld) ("Tenants Architect"), of all improvements that Tenant proposes to
install in the Premises; such working drawings shall include the partition
layout, ceiling plan, electrical outlets and switches, telephone outlets,
drawings for any modifications to the Building's HVAC, electrical, mechanical
and plumbing systems, and detailed plans and specifications for the construction
of the improvements called for under this Exhibit in accordance with all
applicable Laws. Landlord shall notify Tenant whether it approves of the
submitted working drawings within ten business days after Tenant's submission
thereof If Landlord disapproves of such working drawings, then Landlord shall
notify Tenant thereof specifying in reasonable detail the reasons for such
disapproval, in which case Tenant shall, within three business days after such
notice, revise such working drawings in accordance with Landlord's objections
and submit to Landlord for its review and approval. Landlord shall notify Tenant
in writing whether it approves of the resubmitted working drawings within three
business day. after its receipt thereof. This process shall be repeated until
the working drawings have been finally approved by Landlord and Tenant If
Landlord fails to notify Tenant that it disapproves of the initial working
drawings within ten business days (or, in the case of resubmitted working
drawings, within three business days) after the submission thereof, then
Landlord shall be deemed to have approved the working drawings in question.
Further, if any of Tenant's proposed construction work will affect the
Building's HVAC, electrical, mechanical or plumbing systems, then the working
drawings pertaining thereto must be approved by the Building's engineer of
record. Landlord's approval of such working drawings shall not be unreasonably
withheld, provided that (a) they comply with all Laws, (b) such working drawings
are sufficiently detailed to allow construction of the improvements in a good
and workmanlike manner, and (c) the improvements depicted thereon conform to the
rules and regulations promulgated by Landlord for the construction of tenant
improvements in effect as of the date hereof (a copy of which has been delivered
to Tenant). As used herein, "Working Drawings" shall mean the final working
drawings approved by Landlord, as amended from time to time by any approved
changes thereto, and "Work" shall mean all improvements to be constructed in
accordance with and as indicated on the Working Drawings, together with any work
required by governmental authorities to be made to other areas of the Building
as a result of the improvements indicated by the Working Drawings. Landlord's
approval of the Working Drawings shall not be a representation or warranty of
Landlord that such drawings are adequate for any use or comply with any Law, but
shall merely be the consent of Landlord thereto. Tenant shall, at Landlord's
request, sign the Working Drawings to evidence its review and approval thereof
All changes in the Work must receive the prior written approval of Landlord, and
in the event of any such approved change Tenant shall, upon completion of the
Work, finish Landlord with an accurate, reproducible "as-built" plan of the
improvements as constructed.

     3. After the Working Drawings have been approved, Tenant shall cause the
Work to be performed in accordance with the Working Drawings. The Work shall be
performed only by contractors and subcontractors approved in writing by
Landlord, which approval shall not be unreasonably withheld. All contractors and
subcontractors shall be required to procure and maintain insurance against such
risks, in such amounts, and with such companies as Landlord may reasonably
require. Certificates of such insurance, with paid receipts therefor,

                                      D-1
<PAGE>

must be received by Landlord before the Work is commenced. The Work shall be
performed in a good and workmanlike manner free of defects, shall conform
strictly with the Working Drawings, and shall be performed in such a manner and
at such times as and not to interfere with or delay Landlord's other
contractors, the operation of the Building and the occupancy thereof by other
tenants. All contractors and subcontractors shall contact Landlord and schedule
time periods during which they may use Building facilities in connection with
the Work (e.g., elevators, excess electricity, etc.).

     4. The entire cost of performing the Work (including without limitation,
design of the Work and preparation of the Working Drawings, costs of
construction labor and materials, electrical usage during construction,
additional janitorial services, general tenant signage, related taxes and
insurance costs, and the construction supervision fee referenced in Section 8 of
this Exhibit, all of which costs are herein collectively called the "Total
Construction Costs") shall be paid by Tenant

     5. Upon completion of the Work, Tenant shall deliver to Landlord the
following items: (a) final lien waivers from all persons performing work or
supplying or fabricating materials for the Work, fully executed, acknowledged
and in recordable form, (b) Tenant's Architect's certification that the Work has
been finally completed, including any punch-list items, on the appropriate AIA
form or another form approved by Landlord, (c) the permanent certificate of
occupancy issued for the Premises, and (d) an estoppel certificate confirming
such factual matters as Landlord or Landlord's Mortgagee may reasonably request.
Notwithstanding any contrary provision herein, before Tenant may occupy the
Premises to conduct its business therein, Tenant shall, at its expense, obtain
and deliver to Landlord a permanent certificate of occupancy issued for the
Premises by the appropriate governmental authority.

     6. Landlord or its affiliate or agent shall supervise the Work and
coordinate the relationship between the Work, the Building, and the Building's
systems. In consideration for Landlord's construction supervision services,
Tenant shall pay to Landlord a construction supervision fee of $7,500.

     7. To the extent not inconsistent with this Exhibit, Section 8.(a) of this
Lease shall govern the performance of the Work and Landlord's and Tenant's
respective rights and obligations regarding the Improvements installed pursuant
thereto.

     8. Landlord shall not assess any charges for Tenant's use of the loading
docks, passenger and normal use of the freight elevators; however, Landlord
reserves the right to charge Tenant for the extraordinary usage of the freight
elevators (e.g., moving materials on top of elevator cabs). Tenant may use the
freight elevators for moving into the Building subject to prior scheduling with
Landlord and the normal rules and regulations therefor.

     9. Upon approval of the Working Drawings and provided that Tenant delivers
to Landlord evidence that the insurance required under Section 14 of this Lease
and Section 3 of this Exhibit has been obtained, Landlord shall tender
possession of the Premises to Tenant so that Tenant may commence performance of
the Work.

                                       D-2
<PAGE>

                                    EXHIBIT E

                                 AMENDMENT NO. 1

     This Amendment No. 1 (this "Amendment") is executed as of _____________,
199__ between ______________________, a _____________ ("Landlord"),
and____________________, a____________________ ("Tenant"), for the purpose of
amending the Lease Agreement between Landlord and Tenant dated______________,
199___ (the "Lease"). Capitalized terms used herein but not defined shall be
given the meanings assigned to them in the Lease.

                                   AGREEMENTS

     For valuable consideration, whose receipt and sufficiency are acknowledged,
Landlord and Tenant agree as follows:

     1. Condition of Premises. Tenant has accepted possession of the Premises
pursuant to the Lease. All improvements (if any) required by the terms of the
Lease to be made by Landlord have been completed to the full and complete
satisfaction of Tenant in all respects except for the punchlist items described
on Exhibit A hereto (the "Punchlist Items"), and except for such Punchlist
Items, Landlord has fulfilled all of its duties under the Lease with respect to
such initial tenant improvements. Furthermore, Tenant acknowledges that the
Premises are suitable for the Permitted Use.

     2. Commencement Date. The Commencement Date of the Lease is____________,
199__. If the Commencement Date set forth in the Lease is different than the
date set forth in the preceding sentence, then the Commencement Date as
contained in the Lease is amended to be the Commencement Date set forth in the
preceding sentence.

     3. Expiration Date. The Term is scheduled to expire on ________,200_. If
the scheduled expiration date of the initial Term as set forth in the Lease is
different than the date set forth in the preceding sentence, then the scheduled
expiration date as set forth in the Lease is hereby amended to the expiration
date set forth in the preceding sentence.

     4. Contact Numbers. Tenant's telephone number in the Premises is _______.
Tenant's telecopy number in the Premises is_____________.

     5. Ratification. Tenant hereby ratifies and confirms its obligations under
the Lease, and represents and warrants to Landlord that it has no defenses
thereto. Additionally, Tenant further confirms and ratifies that, as of the date
hereto (a) the Lease is and remains in good standing and in full force and
effect, and (b) Tenant has no claims, counterclaims, set-offs or defenses
against Landlord arising out of the Lease or in any way relating thereto or
arising out of any other transaction between Landlord and Tenant.

     6. Binding Effect; Governing Law. Except as modified hereby, the Lease
shall remain in full effect and this Amendment shall be binding upon Landlord
and Tenant and their respective successors and assigns. If any inconsistency
exists or arises between the terms of this Amendment and the terms of the Lease,
the terms of this Amendment shall prevail. This Amendment shall be governed by
the laws of the State in which the Premises is located.

                                      E-1
<PAGE>

     7. Counterparts. This Amendment may be executed in multiple counterparts,
each of which shall constitute an original, but all of which shall constitute
one document

     Executed as of the date first written above.

LANDLORD:                      __________________________,a _______________

                               By:_________________________________________
                               Name:_______________________________________
                               Title:______________________________________

TENANT:                         __________________________,a _______________

                                By:_________________________________________
                                Name:_______________________________________
                                Title:______________________________________

                               E-2
<PAGE>
                                    EXHIBIT F

                       FORM OF TENANT ESTOPPEL CERTIFICATE

     The undersigned is the Tenant under the Lease (defined below)
between_________________, a_______________, as Landlord, and the undersigned as
Tenant, for the Premises on the_______ floor(s) of the office building located
at ______________, _______ and commonly known as _____________________ and
hereby certifies as follows:

     1. The Lease consists of the original Lease Agreement dated as
of_______,199__ between Tenant and Landlord ['s predecessor-in-interest] and the
following amendments or modifications thereto (if none, please state
"none"):________________________________________________________________________
________________________________________________________________________________
_______________________________________________________________________________
_______________________________________________________________________________

The documents listed above are herein collectively referred to as the "Lease"
and represent the entire agreement between the parties with respect to the
Premises. All capitalized terms used herein but not defined shall be given the
meaning assigned to them in the Lease.

     2. The Lease is in full force and effect and has not been modified,
supplemented or amended in any way except as provided in Section 1 above.

     3. The Term commenced on _________, 199__ and the Term expires, excluding
any renewal options, on_________________, 200__, and Tenant has no option to
purchase all or any part of the Premises or the Building or, except as expressly
set forth in the Lease, any option to terminate or cancel the Lease.

     4. Tenant currently occupies the Premises described in the Lease and Tenant
has not transferred, assigned, or sublet any portion of the Premises nor entered
into any license or concession agreements with respect thereto except as follows
(if none, please state "none"):_________________________________________________
________________________________________________________________________________
________________________________________________________________________________
________________________________________________________________________________

     5. All monthly installments of Basic Rent, all Additional Rent, Operating
Costs, and monthly installments of estimated Operating Costs have been paid when
due through _____________ . The current monthly installment of Basic Rent is
$_________ .

     6. All conditions of the Lease to be performed by Landlord necessary to the
enforceability of the Lease have been satisfied and Landlord is not in default
thereunder. In addition, Tenant has not delivered any notice to Landlord
regarding a default by Landlord thereunder.

     7. As of the date hereof there are no existing defenses or offsets, or, to
the undersigned's knowledge, claims or any basis for a claim, that the
undersigned has against Landlord and no event has occurred and no condition
exists, which, with the giving of notice or the passage of time, or both, will
constitute a default under the Lease.

                                       F-1
<PAGE>

     8. No rental has been paid more than thirty (30) days in advance and no
security deposit has been delivered to Landlord except as provided in the Lease.

     9. If Tenant is a corporation, partnership or other business entity, each
individual executing this Estoppel Certificate on behalf of Tenant hereby
represents and warrants that Tenant is a duly formed and existing entity
qualified to do business in the state in which the Premises is located and that
Tenant has full right and authority to execute and deliver this Estoppel
Certificate and that each person signing on behalf of Tenant is authorized to do
so.

     10. There are no actions pending against Tenant under any bankruptcy or
similar laws of the United States or any state.

     11. Other than in compliance with all applicable laws and incidental to the
ordinary course of the use of the Premises, the undersigned has not used or
stored any hazardous substances in the Premises.

     12. All tenant improvement work to be performed by Landlord under the Lease
has been completed in accordance with the Lease and has been accepted by the
undersigned and all reimbursements and allowances due to the undersigned under
the Lease in connection with any tenant improvement work have been paid in full.

     Tenant acknowledges that this Estoppel Certificate may be delivered to
Landlord, Landlord's Mortgagee or to a prospective mortgagee or prospective
purchaser, and their respective successors and assigns, and acknowledges that
Landlord, Landlord's Mortgagee and/or such prospective mortgagee or prospective
purchaser will be relying upon the statements contained herein in disbursing
loan advances or making a new loan or acquiring the property of which the
Premises are a part and that receipt by it of this certificate is a condition of
disbursing loan advances or making such loan or acquiring such property.

       Executed as of ________________.

TENANT:                         __________________________,a _______________

                                By:_________________________________________
                                Name:_______________________________________
                                Title:______________________________________

                                       F-2
<PAGE>

                                    EXHIBIT H

                                 RENEWAL OPTIONS

     Provided no Event of Default exists and Tenant is occupying the entire
Premises at the time of such election, Tenant may renew this Lease for two (2)
additional period(s) of five (5) years each, by delivering written notice of the
exercise thereof to Landlord not earlier than nine months nor later than six
months before the expiration of the Term. On or before the commencement date of
the extended Term in question, Landlord and Tenant shall execute an amendment to
this Lease extending the Term on the same terms provided in this Lease, except
as follows:

          (a) The Basic Rent and Additional Rent payable for each month during
     such extended Term shall be the greater of (1) the prevailing rental rate
     in the building at the commencement of such extended Term, for space of
     equivalent quality, size, utility and location, with the length of the
     extended Term and the credit standing of Tenant to be taken into account,
     or (2) the total monthly Basic Rent and Additional Rent last payable
     hereunder for the month immediately preceding the commencement date of the
     extended Term in question multiplied by 1.03;

          (b) Tenant shall have no further renewal option unless expressly
     granted by Landlord in writing; and

          (c) Landlord shall lease to Tenant the Premises in their then-current
     condition, and Landlord shall not provide to Tenant any allowances (e.g.,
     moving allowance, construction allowance, and the like) or other tenant
     inducements.

     Tenant's rights under this Exhibit shall terminate if (1) this Lease or
Tenant's right to possession of the Premises is terminated, (2) Tenant assigns
any of its interest in this Lease or sublets any portion of the Premises, (3)
Tenant fails to timely exercise its option under this Exhibit, time being of the
essence with respect to Tenant's exercise thereof, or (4) Landlord determines,
in its sole but reasonable discretion, that Tenant's financial condition or
creditworthiness has materially deteriorated since the date of this Lease.

                                       H-1
<PAGE>

                                    EXHIBIT I

                            RENT ABATEMENT PROVISIONS

     Basic Rent shall be conditionally abated until March 31, 2000 Commencing on
April 1,2000, Tenant shall make Basic Rent payments as otherwise provided in the
Lease. Notwithstanding such abatement of Basic Rent all other sums due under the
Lease, including Additional Rent shall be payable as provided in the Lease, and
any increases in Basic Rent set forth in the Lease shall occur on the dates
scheduled therefor.

     The abatement of Basic Rent provided for in this Exhibit is conditioned
upon Tenant's full and timely performance of all of its obligations under the
Lease. If at any time during the Term an Event of Default by Tenant occurs, then
the abatement of Basic Rent provided for in this Exhibit shall immediately
become void, and Tenant shall promptly pay to Landlord, in addition to all other
amounts due to Landlord under this Lease, the full amount of all Basic Rent
herein abated.

                                      J-1<PAGE>
                                                                 Exhibit 10.1.10

                                      THE
                                 PITTOCK BLOCK

                                     LEASE

                        Between ALCO INVESTMENT COMPANY,
                            a Washington corporation
                                  ("Landlord")

                                      and

                       ADVANCED TELECOMMUNICATIONS, INC.,
                             a Delaware corporation
                                   ("Tenant")
<PAGE>

                                     LEASE

THIS LEASE is made and entered into this 19th day of November, 1999, between
ALCO INVESTMENT COMPANY, a Washington corporation ("Landlord"), and ADVANCED
TELECOMMUNICATIONS, INC., a Delaware corporation ("Tenant")

1.   BASIC LEASE PROVISIONS
     AND IDENTIFICATION OF
     ADDENDA AND EXHIBITS.
<TABLE>
<S>                              <C>                      <C>
11.  Basic Lease Provisions.     LEASED PREMISES:         See Exhibit B, containing approximately 4,878 square feet of rentable
                                                          floor area

                                 ADDRESS:                 921 SW Washington Street, Suite 410 Portland Oregon 97205

                                 LEASE TERM:              Ten (10) years

                                 COMMENCEMENT DATE:       January 1, 2000

                                 EXPIRATION DATE:         December 31, 2009

                                 MONTHLY BASE RENT:       Years 1-5:        $7,723.00 per month (see Base Rent Escalation Addendum
                                                                            and Emergency Generator Connection Fee Addendum for
                                                                            additional Monthly Base Rent payments)

                                                          Years 6-10:       adjusted to market rental rate of the Building pursuant
                                                                            to Market Rental Adjustment Addendum attached hereto

                                 APPLICABLE PERCENTAGE:   One and nine tenths of one percent (1.9%) (see Subsection 4.2(a))

                                 PERMITTED USES:          Location and operation of telecommunications equipment and general
                                                          offices.

                                 TENANTS REPRESENTATIVE:  Satish Tiwari

                                 BROKER:                  Alco Properties

                                 ADDENDA:                 BASE RENT ESCALATION, MARKET RENTAL ADJUSTMENT, COOLING TOWER CONNECTION
                                                          FEE, ELECTRICAL CONNECTION FEE, EMERGENCY GENERATOR CONNECTION FEE,
                                                          CONNECTIVITY RIGHT, RULES AND REGULATIONS
</TABLE>

1.2  Identification of           The exhibits and addenda, if any, identified in
     Exhibits and Addenda.       and attached to this Lease are incorporated in
                                 this Lease by reference.

2.   LEASED PREMISES.

2.1  Leased Premises.            Landlord hereby leases to Tenant, and Tenant
                                 hereby accepts from Landlord, subject to and
                                 with the benefit of the terms and provisions of
                                 this Lease, the Leased Premises located in the
                                 improvements which are located on the real
                                 property described in Exhibit A and depicted in
                                 Exhibit B. The real property and improvements
                                 are hereinafter referred to as the "Building".

                                       1
<PAGE>

2.2  Tenant Improvements         Tenant accepts the Leased Premises in "as is"
     Provisions.                 condition.

3.   TERM.                       This Lease shall be for a term ("Term") which
                                 commences on the Commencement Date and expires
                                 on the Expiration Date. The "Commencement Date"
                                 shall be the date listed in Section 1.1.

4.   RENT AND OTHER CHARGES.

4.1  Monthly Base Rent.          Commencing on the Commencement Date, Tenant
                                 shall pay to Landlord, without notice or demand
                                 and without any set-off or deduction
                                 whatsoever, the monthly sums set forth in
                                 Subsection 1.1 above (the "Monthly Base Rent")
                                 which tenant shall pay in advance on or before
                                 the first day of each calendar month of the
                                 Term. If the Term commences on a day other than
                                 the first day of a calendar month, the Monthly
                                 Base Rent for such month shall be a prorated
                                 portion of the Monthly Base Rent, based upon a
                                 thirty (30) day month.

4.2  Other Charges.              In addition to the Monthly Base Rent, Tenant
                                 shall pay to Landlord in the manner' provided
                                 in Subsection 4.2(b), Tenant's share of the
                                 Insurance and Taxes described in Subsection
                                 4.2(a) (hereinafter together called "Other
                                 Charges").

     (a)  Other Charges.              (i) Tenant shall pay to Landlord Tenant's
                                 share of the Insurance and Taxes of the
                                 Building for each Lease Year, or portion
                                 thereof, during the Term. Tenant's share shall
                                 be equal to the Applicable Percentage,
                                 multiplied by the amount of the total Insurance
                                 and Taxes during each Lease Year. The term
                                 "Insurance" means the total cost and expense
                                 for Insurance of the Building, including but
                                 not limited to, the fire and extended coverage
                                 insurance (with an earthquake endorsement);
                                 public liability and property damage insurance;
                                 and rent insurance.

                                     (ii) The term "Taxes" means taxes on real
                                 property and personal property, including all
                                 tenant improvements which are paid for by
                                 Landlord and not reimbursed by tenants, and
                                 taxes on property of tenants of the Building
                                 which have not been paid by such tenants
                                 directly to the taxing authority; charges and
                                 assessments levied with respect to the
                                 Building, any improvements, fixtures and
                                 equipment, and all other property of Landlord,
                                 real or personal, used directly in the
                                 operation of the Building, and located in or on
                                 the Building; and any taxes levied or assessed
                                 in addition to or in lieu of, in whole or in
                                 part, such real property or personal property
                                 taxes, or any other tax upon leasing of the
                                 Building or rents collected, but excluding any
                                 federal or state income tax or franchise tax.

     (b)  Payment of Other       Prior to the first day of each Lease Year of
          Charges.               the Term (or as soon thereafter as such
                                 information becomes available) Landlord will
                                 notify Tenant in writing of Landlord's estimate
                                 of Tenant's share of the Other Charges due for
                                 the next Lease Year. Landlord's estimate shall
                                 be based upon the actual amount of the Other
                                 Charges for the immediately preceding Lease
                                 Year and Landlord's estimate of Other Charges
                                 for the next Lease Year. Tenant shall pay the
                                 estimated Tenant's share in advance in twelve
                                 (12) equal monthly installments on

                                       2
<PAGE>

                                 the first day of each month of such year.
                                 Within thirty (30) days after the end of each
                                 Lease Year, Landlord will compute Tenant's
                                 share for such Lease Year based upon the actual
                                 amount of the Other Charges for that Lease
                                 Year, and if the total amount paid by Tenant
                                 for such Lease Year is less than the actual
                                 amount of Tenant's share for such Lease Years,
                                 Tenant shall pay Landlord any deficiency. If
                                 the total amount paid by Tenant for such Lease
                                 Year exceeds the actual amount of Tenant's
                                 share, Landlord shall credit such excess to the
                                 next monthly payments of Other Charges which
                                 thereafter come due. If the Term commences at a
                                 time other than the beginning of a Lease Year,
                                 Tenant shall pay the estimate of Tenant's share
                                 for the portion remaining of the Lease Year
                                 based upon the number of days of the Term in
                                 such Lease Year. If this Lease expires at a
                                 time other than the expiration date of a Lease
                                 Year, Tenant shall be obligated to pay
                                 immediately any deficiencies which shall be
                                 computed at the expiration of that Lease Year.
                                 If the estimated amount Tenant has paid for
                                 that Lease Year exceeds the actual amount of
                                 Tenant's share, Landlord shall refund such
                                 excess to Tenant. If at any time during a Lease
                                 Year the amount of the Other Charges increases
                                 over the estimated amount, Landlord may, at its
                                 election, adjust the amount of monthly
                                 estimated installments due during the balance
                                 of that Lease Year to reflect such increase.
                                 Any increased payments required to be made
                                 pursuant to this Subsection shall be made
                                 within thirty (30) days after Landlord has
                                 notified Tenant thereof. Tenant's obligations
                                 under this Subsection shall survive the
                                 expiration or termination of this Lease.

4.3  Late Charges.               If Tenant fails to pay when the same is due and
                                 payable, any Monthly Base Rent or any
                                 additional rent, such unpaid amounts shall bear
                                 interest at the rate of eighteen percent (18%)
                                 per annum from the date due to the date of
                                 payment, but in no event in excess of the
                                 maximum rate, if any, permitted by applicable
                                 law. In addition to such interest, if any
                                 Monthly Base Rent installment is not received
                                 by Landlord from Tenant by the tenth (10th) day
                                 of the month for which such installment is due,
                                 Tenant shall immediately pay to Landlord a
                                 late charge equal to five percent (5%) of each
                                 installment.

5.   PERSONAL PROPERTY TAXES.    Tenant shall pay, or cause to be paid, before
                                 delinquency, any and all taxes levied or
                                 assessed during the Term upon all Tenant's
                                 leasehold improvements, equipment, furniture,
                                 fixtures, and any other personal property
                                 located in the Leased Premises.

6.   LICENSES AND TAXES.         Tenant shall be liable for, and shall pay
                                 throughout the Term, all license and excise
                                 fees and business and occupation taxes covering
                                 the business conducted on the Leased Premises.
                                 If any governmental authority or unit under any
                                 present or future law effective at any time
                                 during the Term hereof shall in any manner levy
                                 a tax on rents payable under this Lease or
                                 rents accruing from use of the Leased Premises
                                 or a tax in any form against Landlord because
                                 of or measured by income derived from the
                                 leasing or rental of such property, such tax
                                 shall be paid by Tenant, either directly or
                                 through Landlord. Upon Tenant's failure to pay
                                 such amounts, Landlord shall have the same
                                 remedies as for failure to pay rent. Tenant
                                 shall not be liable to pay any net income tax
                                 imposed on Landlord.

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<PAGE>

7.   USE.

7.1  Permitted Uses.             Tenant shall not use or permit or suffer the
                                 use of the Leased Premises for any business or
                                 purpose other than set forth in Subsection 1.1
                                 above. Tenant shall not do or permit anything
                                 to be done in or about the Leased Premises or
                                 bring or keep anything therein which will in
                                 any way increase the existing rate or premiums
                                 of, or affect any, fire or other insurance upon
                                 the Leased Premises or the Building, or cause a
                                 cancellation of any insurance policy covering
                                 the Leased Premises or the Building or any part
                                 thereof or any of its contents. Tenant shall
                                 not do or permit or suffer anything to be done
                                 in or about the Leased Premises which will in
                                 any way obstruct or interfere with the rights
                                 of other tenants or occupants in the Building.
                                 Tenant shall, at its sole cost and expense,
                                 promptly comply with all local, state or
                                 federal laws.

7.2  Hazardous Waste and         Tenant shall not dispose of or otherwise allow
     Materials.                  the release of any hazardous waste or materials
                                 in, on or under the Leased Premises, or any
                                 adjacent property, or in any improvements
                                 placed on the Leased Premises. Tenant
                                 represents and warrants to Landlord that
                                 Tenant's intended use of the Premises does not
                                 involve the use, production, disposal or
                                 bringing on to the Leased Premises of any
                                 hazardous waste or materials. As used herein,
                                 the term "hazardous waste or materials"
                                 includes any substance, waste or material
                                 defined or designated as hazardous, toxic or
                                 dangerous (or any similar term) by any federal,
                                 state or local statute, regulation, rule or
                                 ordinance now or hereafter in effect. Tenant
                                 shall promptly comply with all statutes,
                                 regulations and ordinances, and with all
                                 orders, decrees or judgments of governmental
                                 authorities or courts having jurisdiction,
                                 relating to the use, collection, treatment,
                                 disposal, storage, control, removal or cleanup
                                 of hazardous waste or materials in, on or under
                                 the Leased Premises or any adjacent property,
                                 or incorporated in any improvements, at
                                 Tenant's expense.

                                 Tenant shall not allow smoke of any kind in the
                                 Leased Premises, including but not limited to,
                                 smoke from cigarettes, pipes and cigars unless
                                 Tenant provides, at Tenant's sole expense, an
                                 air supply and exhaust system which is one
                                 hundred percent separated from the Building air
                                 system shared with other tenants.

                                 After notice to Tenant and a reasonable
                                 opportunity for Tenant to effect such
                                 compliance, Landlord may, but is not obligated
                                 to, enter upon the Leased Premises and take
                                 such actions and incur such costs and expenses
                                 to effect such compliance as it deems advisable
                                 to protect its interest in the Leased Premises;
                                 provided, however, that Landlord shall not be
                                 obligated to give Tenant notice and an
                                 opportunity to effect such compliance if (1)
                                 such delay might result in material adverse
                                 harm to Landlord or the Leased Premises, (2)
                                 Tenant has already had actual knowledge of the
                                 situation and a reasonable opportunity to
                                 effect such compliance, or (3) an emergency
                                 exists. Whether or not Tenant has actual
                                 knowledge of the release of hazardous waste or
                                 materials on the Premises or any adjacent
                                 property as the result of Tenant's use of the
                                 Leased Premises, Tenant shall reimburse
                                 Landlord for the full amount of all costs and
                                 expenses incurred by

                                       4
<PAGE>

                                 Landlord in connection with such compliance
                                 activities, and such obligation shall continue
                                 even after the termination of this Lease.
                                 Tenant shall notify Landlord immediately of any
                                 release of any hazardous waste or materials on
                                 the Leased Premises.

                                 Tenant agrees to indemnify and hold Landlord
                                 harmless against any and all losses,
                                 liabilities, suits, obligations, fines,
                                 damages, judgments, penalties, claims, charges,
                                 cleanup costs, remedial actions, costs and
                                 expenses (including, without limitations,
                                 attorneys' fees and disbursements) which may be
                                 imposed on, incurred or paid by, or asserted
                                 against Landlord or the Premises by reason of,
                                 or in connection with (1) any
                                 misrepresentation, breach of warranty or other
                                 default by Tenant under this Lease, or (2) the
                                 acts or omissions of Tenant, or any subtenant
                                 or other person for whom Tenant would otherwise
                                 be liable, resulting in the release of any
                                 hazardous waste or materials.

                                 Tenant acknowledges that the Premises may
                                 contain asbestos materials, and Tenant accepts
                                 the Premises and the Building notwithstanding
                                 such materials. If Landlord is required by any
                                 statute, regulation, order, decree, judgment,
                                 or other law to take any action to remove or
                                 abate the asbestos materials, or if Landlord
                                 deems it necessary to conduct special
                                 maintenance or testing procedures with regard
                                 to the asbestos materials, or to remove or
                                 abate such asbestos material, Landlord may take
                                 such action or conduct such procedures at times
                                 and in a manner that Landlord deems appropriate
                                 under the circumstances, and Tenant shall
                                 permit the same.

8.   ALTERATIONS.                Tenant shall not make any alterations,
                                 additions, or improvements in or to the Leased
                                 Premises without the prior written consent of
                                 Landlord, which consent may be subject to such
                                 conditions as Landlord may deem appropriate but
                                 which consent shall not be unreasonably
                                 withheld or delayed. Landlord shall use its
                                 best efforts to expedite review and approval of
                                 Tenant's alteration plans when Tenant's
                                 schedule requires expedited review. Except as
                                 otherwise expressly provided in the Tenant
                                 Improvements Provisions, any such alterations,
                                 additions or improvements consented to by
                                 Landlord shall be made at Tenant's sole cost
                                 and expense. Tenant shall secure any and all
                                 governmental permits, approvals or
                                 authorizations required in connection with any
                                 such work, and shall hold Landlord harmless
                                 from any and all liability, costs, damages,
                                 expenses (including attorneys' fees) and any
                                 and all liens resulting therefrom. All
                                 alterations, additions and improvements (and
                                 expressly including all light fixtures and
                                 floor coverings), except trade fixtures and
                                 other equipment which do not become a part of
                                 the Leased Premises, shall immediately become
                                 the property of Landlord without any obligation
                                 to pay therefore. Upon the expiration or sooner
                                 termination of the Term, Tenant shall, upon
                                 written demand by Landlord, given at least
                                 thirty (30) days prior to the end of the Term,
                                 at Tenant's sole cost and expense forthwith
                                 remove any trade fixtures of Tenant designated
                                 by Landlord to be removed, but not alterations,
                                 additions or improvements made by Tenant, and
                                 Tenant shall forthwith at its sole cost and
                                 expense, repair any damage to the Leased
                                 Premises caused by such removal of trade
                                 fixtures.

                                       5
<PAGE>

9.   MAINTENANCE, REPAIRS AND
     SERVICES.

9.1  Maintenance and Repairs     Landlord shall repair and maintain in good
     by Landlord.                order and condition the public and common areas
                                 of the Building, including lobbies, stairs,
                                 elevators, corridors, restrooms, windows,
                                 mechanical, plumbing and electrical equipment
                                 and the structure itself. However, if such
                                 maintenance and repair becomes necessary in
                                 whole or in part due to the act, neglect, fault
                                 or omission of any duty by Tenant, its
                                 employees, agents, licensees, customers, guests
                                 or invitees, or due to damage caused by actual
                                 or attempted breaking and entering of the
                                 Leased Premises or other unauthorized entry of
                                 the Leased Premises, such maintenance and
                                 repair shall be undertaken by Landlord at
                                 Tenant's expense. There shall be no abatement
                                 of rent and no liability of Landlord by reason
                                 of any interference with Tenant's business
                                 arising from the making of any repairs,
                                 alterations or improvements to any portion of
                                 the Leased Premises, the Building, or to
                                 fixtures, appurtenances and equipment therein
                                 so long as Landlord is making reasonable good
                                 faith efforts to minimize such interference.

9.2  Maintenance and Repairs     Tenant by occupying the Leased Premises accepts
     by Tenant.                  same as being in good and tenantable condition
                                 in accordance with Landlord's obligations.
                                 Tenant shall at Tenant's sole expense keep the
                                 Leased Premises and all interior partitions,
                                 door surfaces, fixtures, equipment and
                                 appurtenances (including lighting and plumbing
                                 fixtures) in good and sanitary condition and
                                 repair, ordinary wear and tear excepted;
                                 provided, however, with respect to such items
                                 that are shared with other tenants of the
                                 Building, Tenant shall pay its pro-rata share
                                 of such expenses. Tenant shall at the
                                 expiration or termination of the Term surrender
                                 to Landlord the Leased Premises and all
                                 alterations, additions and improvements in the
                                 same condition as when received, ordinary wear
                                 and tear excepted. Landlord has no obligation
                                 and has made no promise to alter, remodel,
                                 improve, or repair the Leased Premises or any
                                 part thereof, except as specifically set forth
                                 in this Lease. Tenant also acknowledges that
                                 Landlord has made no representations or
                                 warranties respecting the condition of the
                                 Leased Premises or the Building, except as
                                 specifically set forth in this Lease. If any
                                 standard or regulation is imposed on Landlord
                                 or Tenant by any federal, state or local
                                 governmental or quasi-governmental body charged
                                 with the establishment, regulation and
                                 enforcement of occupational, health or safety
                                 standards for employers, employees, landlords
                                 or tenants, then Tenant agrees, at its sole
                                 cost and expense, to comply promptly with such
                                 standards or regulations with respect to the
                                 Leased Premises.

9.3  Failure to Maintain.        If Tenant fails to keep and preserve the Leased
                                 Premises as set forth in Subsection 9.2 above,
                                 Landlord may, at its option, put or cause the
                                 same to be put in the condition and state of
                                 repair agreed upon, and in such case, upon
                                 receipt of written statements from Landlord,
                                 Tenant shall promptly pay the entire cost
                                 thereof. Landlord shall have the right, without
                                 liability, to enter the Leased Premises for the
                                 purpose of making such repairs upon the failure
                                 of Tenant to do so with fifteen (15) days'
                                 notice to Tenant, unless Landlord deems entry
                                 necessary without notice due to an emergency.

                                       6
<PAGE>

9.4  Surrender of Leased         At the expiration or sooner termination of this
     Premises.                   Lease, Tenant shall return the Leased Premises
                                 to Landlord in the same condition in which
                                 received (or, if altered by Landlord or by
                                 Tenant with the Landlord's consent, then the
                                 Leased Premises shall be returned in such
                                 altered condition), reasonable wear and tear
                                 excepted. Tenant shall remove all trade
                                 fixtures, appliances and equipment which do not
                                 become a part of the Leased Premises and shall
                                 restore the Leased Premises to the condition
                                 they were in prior to the installation of such
                                 items, reasonable wear and tear excepted.

9.5  Services.                   Landlord shall furnish the Leased Premises
                                 with:

                                      (a) Cooling tower water pursuant to the
                                 attached Cooling Tower Connection Fee Addendum;

                                      (b) Electrical service pursuant to the
                                 attached Electrical Connection Fee Addendum;
                                 and

                                      (c) Emergency generator service pursuant
                                 to the attached Emergency Generator Fee
                                 Addendum.

9.6  Landlord's Duties.          Landlord shall not be in default under this
                                 Lease or liable for any damages resulting from
                                 or incidental to, nor shall it be an actual or
                                 constructive eviction of the Tenant, nor shall
                                 the rent be abated by reason of:

                                      (a) The interruption of use of any
                                 equipment in connection with the furnishing of
                                 any of the services described in this Section
                                 9;

                                      (b) Failure to furnish or delay in
                                 furnishing any such services when such failure
                                 or delay is caused by accident or any condition
                                 beyond the reasonable control of Landlord,
                                 including the making of necessary repairs or
                                 improvements to the Leased Premises or to the
                                 Building/systems;

                                      (c) Any limitation, curtailment, rationing
                                 restrictions on the use of electricity, water,
                                 gas or other form of energy serving the Leased
                                 Premises or the Building; or

                                      (d) Failure to make any repair or to
                                 perform any maintenance, unless such failure
                                 shall persist for an unreasonable time after
                                 written notice of the need for such repair or
                                 maintenance is given to Landlord by Tenant.

                                 Landlord shall use its commercially best
                                 efforts to remedy any interruption in the
                                 furnishing of such services.

9.7   Governmental               Any other provisions of this Section 9
      Regulations.               notwithstanding, if any governmental agency or
                                 utility supplier imposes any regulations,
                                 controls, conditions, or other restrictions
                                 upon Landlord, Tenant, or the Building, which
                                 require or make desirable a change in the
                                 services provided by Landlord under this Lease
                                 or the lighting or equipment used by Tenant on
                                 the Leased Premises, Landlord may comply and
                                 may require Tenant to comply with such
                                 regulations, controls, conditions or
                                 restrictions without Landlord being in default
                                 under this

                                       7
<PAGE>

                                 Lease or liable for any damages to Tenant and
                                 without said actions constituting an actual or
                                 constructive eviction of Tenant or entitling
                                 Tenant to any abatement of rent, providing that
                                 Tenant is able to conduct its ordinary and
                                 customary business in the Leased Premises.
                                 Without limiting the generality of the
                                 foregoing, it shall specifically include
                                 curtailment, rationing, or restrictions on the
                                 use of electricity and other sources of power,
                                 and recommended or mandated changes in
                                 temperatures to be maintained in the Building
                                 or Leased Premises.

9.8  Electricity Use.            Tenant shall pay for the cost of furnishing the
                                 Leased Premises with metered electrical service
                                 from Landlord's Electrical Service Gear
                                 pursuant to the attached Electrical Connection
                                 Fee Addendum. Tenant shall reimburse Landlord
                                 for all electrical energy used in the Leased
                                 Premises. In no event shall the Tenant's use of
                                 electricity exceed the capacity of existing
                                 feeders to the Building or the risers or wiring
                                 installation, and the Landlord may prohibit the
                                 use of any electrical equipment which in the
                                 Landlord's opinion will overload such wiring or
                                 interfere with the use thereof by other tenants
                                 in the Building. If Landlord consents to the
                                 use of equipment requiring such changes, Tenant
                                 shall pay the cost of installing any additional
                                 risers, panels or other facilities that may be
                                 necessary to furnish energy to the Leased
                                 Premises.

9.9  Conservation.               Tenant shall use its best efforts to recycle
                                 its waste and to conserve heat, air
                                 conditioning, electricity and water usage on
                                 the Leased Premises.

10.  LIENS AND ENCUMBRANCES.     Tenant shall keep the Leased Premises and the
                                 Building, free from any liens or encumbrances
                                 arising out of any work performed, materials
                                 furnished or obligations incurred by Tenant,
                                 and shall indemnify and hold Landlord harmless
                                 from any and all costs, liability or expenses
                                 (including attorneys' fees) arising therefrom.

11.  ASSIGNMENT AND              Tenant shall not assign, transfer, mortgage,
     SUBLETTING.                 pledge, hypothecate or encumber this Lease or
                                 any interest therein, nor sublet the whole or
                                 any part of the Leased Premises, nor shall this
                                 Lease or any interest hereunder be assignable
                                 or transferable by operation of law or by any
                                 process or proceeding of any court, or
                                 otherwise without the consent of Landlord.
                                 Landlord reserves the right to refuse to give
                                 such consent if in Landlord's reasonable
                                 business judgment the quality of business
                                 experience or the financial worth of the
                                 proposed new tenant is less than that of
                                 Tenant. For the purposes hereof, if Tenant is a
                                 partnership, a transfer of a general partner's
                                 interests in a partnership shall be deemed an
                                 assignment. For the purposes hereof, a
                                 consolidation or merger of Tenant (or if Tenant
                                 is a partnership, one or more of whose partners
                                 is a corporation, then of such corporation(s),
                                 or a change in more than fifty percent (50%) of
                                 the issued and outstanding voting or non-voting
                                 stock of Tenant (or if Tenant is a partnership,
                                 one or more of whose partners is a corporation,
                                 then of such corporation(s) shall be deemed as
                                 assignment. Tenant agrees to reimburse Landlord
                                 for Landlord's reasonable attorneys' fees
                                 incurred in conjunction with the proceeding and
                                 documentation of any such requested transfer,
                                 assignment, subletting, licensing or concession
                                 agreement, change of fee ownership or

                                       8
<PAGE>

                                 hypothecation of this Lease or Tenant's
                                 interest in the Leased Premises.

12.  INSURANCE AND INDEMNITY.

12.1 Indemnification.            Landlord shall not be liable for injury to any
                                 person, or for the loss of or damage to any
                                 property (including property of Tenant)
                                 occurring in or about the Leased Premises from
                                 any cause whatsoever, except for Landlord's
                                 negligent acts or willful misconduct. Tenant
                                 hereby indemnifies and holds Landlord harmless
                                 from and against and agrees to defend Landlord
                                 against any and all claims, charges,
                                 liabilities, obligations, penalties, damages,
                                 costs and expenses (including attorneys' fees)
                                 arising, claimed, charged or incurred against
                                 or by Landlord from any matter or thing arising
                                 from Tenant's use of the Leased Premises, the
                                 conduct of its business or from any activity,
                                 work or other things done, permitted or
                                 suffered by the Tenant in or about the Leased
                                 Premises, and Tenant shall further indemnify
                                 and hold Landlord harmless from and against any
                                 and all claims arising from any breach or
                                 default in the performance of any obligation on
                                 Tenant's part or to be performed under the
                                 terms of this Lease, or arising from any act or
                                 negligence of the Tenant, or any officer,
                                 agent, employee, guest, or invitee of Tenant,
                                 and from all costs, attorneys' fees, and
                                 liabilities incurred in or about the defense of
                                 any such claim or any action or proceeding
                                 brought thereon; and in case any action or
                                 proceeding be brought against Landlord by
                                 reason of such claim; Tenant, upon notice from
                                 Landlord, shall defend the same at Tenant's
                                 expense by counsel reasonably satisfactory to
                                 Landlord. The indemnification provided for in
                                 this paragraph with respect to any acts or
                                 omissions during the term of this Lease shall
                                 survive any termination or expiration of this
                                 Lease. Landlord shall not be liable for
                                 interference with light or air or view or for
                                 any latent defect in the Leased Premises.
                                 Tenant shall promptly notify Landlord of
                                 casualties or accidents occurring in or about
                                 the Leased Premises. In the event of concurrent
                                 negligence of Tenant, its agents, employees,
                                 sublessees, invitees, licensees or contractors
                                 on the one hand, and that of Landlord, its
                                 partners, directors, officers, agents,
                                 employees, or contractors on the other hand,
                                 which concurrent negligence results in the
                                 injury or damage to persons or property and
                                 relates to the construction, alteration,
                                 repair, addition to, subtraction from,
                                 improvement to or maintenance of the Leased
                                 Premises, common areas or buildings, Tenant's
                                 obligation to indemnify Landlord as set forth
                                 in this Section shall be limited to the extent
                                 of Tenant's negligence, and that of its agents,
                                 employees, sublessees, invitees, licensees or
                                 contractors, including Tenant's proportional
                                 share of costs, including attorneys' fees and
                                 expenses incurred in connection with any claim,
                                 action or proceeding brought with respect to
                                 such injury or damage. Tenant and Landlord
                                 further agree that this indemnification
                                 provision has been specifically negotiated and
                                 agreed to the parties hereto. Any
                                 indemnification of Landlord provided for in
                                 this Lease shall include Landlord and its
                                 property manager and their officers, employees
                                 and agents.

12.2 Insurance.                  During the entire Term of this lease Tenant
                                 shall, at its expense, maintain adequate
                                 liability insurance with a reputable insurance
                                 company or companies with a combined

                                       9
<PAGE>

                                 single limit of $1,000,000 for personal
                                 injuries or property damage, to indemnify both
                                 Landlord and Tenant against any such claims,
                                 demands, losses, damages, liabilities and
                                 expenses. Landlord shall be named as one of the
                                 insureds and shall be furnished with a
                                 certificate of such insurance, which shall bear
                                 an endorsement that the same shall not be
                                 canceled except upon not less than twenty (20)
                                 days' prior written notice to Landlord. Tenant
                                 shall also at its own expense maintain, during
                                 the Term, all-risk insurance covering its
                                 furniture, fixtures, equipment and inventory in
                                 an amount equal to the replacement cost
                                 thereof, and insurance covering all plate glass
                                 and other glass on the Leased Premises. Tenant
                                 shall provide Landlord with copies of the
                                 policies of insurance or certificates thereof.

12.3 Increase in Insurance       Tenant shall not keep, use, sell or offer for
     Premium.                    sale in or upon the Leased Premises any article
                                 which may be prohibited by the standard form of
                                 fire insurance policies. Tenant shall pay any
                                 increase in premium for casualty and fire
                                 (including extended coverage) insurance that
                                 may be charged during the Term on the amount of
                                 such insurance which may be carried by Landlord
                                 on the Leased Premises or the Building,
                                 resulting from Tenant's occupancy or from the
                                 type of property which Tenant stores on the
                                 Leased Premises, whether or not Landlord has
                                 consented thereto. In such event, Tenant shall
                                 also pay any additional premium on the
                                 insurance policy that Landlord may carry for
                                 its protection against rent loss through fire
                                 or casualty.

12.4 Waiver of Subrogation.      Landlord and Tenant hereby mutually release
                                 each other from liability and waive all right
                                 of recovery against each other, their agents or
                                 employees, for any loss in or about the Leased
                                 Premises, from perils insured against under
                                 their respective fire and all-risk insurance
                                 contracts, including any extended coverage
                                 endorsements thereof, whether due to negligence
                                 or any other cause; provided that this
                                 subsection shall be inapplicable if it would
                                 have the effect, but only to the extent it
                                 would have the effect, of invalidating any
                                 insurance coverage of Landlord or Tenant.

13.  EMINENT DOMAIN.

13.1 Taking.                     If all or part of the Leased Premises are taken
                                 by the power of eminent domain exercised by any
                                 governmental or quasi-governmental authority,
                                 this Lease shall terminate as of the date
                                 Tenant is required to vacate the Leased
                                 Premises and all Monthly Base Rent and other
                                 rentals and charges due hereunder shall be paid
                                 to that date. The term "eminent domain" shall
                                 include the taking or damaging of property by,
                                 through or under any governmental or
                                 quasi-governmental authority, and any purchase
                                 or acquisition in lieu thereof, whether or not
                                 the damaging or taking is by government or any
                                 other person. If part of the Building is taken
                                 or appropriated but no portion of the Leased
                                 Premises is taken or appropriated, this Lease
                                 may, at the option of the Landlord, be
                                 terminated by written notice given to the
                                 Tenant not more than thirty (30) days after
                                 Landlord receives notice of the taking or
                                 appropriation. If part of the Building is taken
                                 or appropriated but no portion of the Leased
                                 Premises is taken or appropriated and if such
                                 taking or appropriation has a material adverse
                                 affect on Tenant's business this Lease may, at
                                 the option of Tenant, be terminated by written
                                 notice

                                       10
<PAGE>

                                 given to Landlord within sixty (60) days of
                                 receipt of notice by Tenant of such proposed
                                 taking. Such terminations shall be effective as
                                 of the date when the Landlord or its tenants
                                 are required to vacate the portion of the
                                 Building so taken.

13.2 Damages.                    Landlord reserves all rights to the entire
                                 damage award or payment for any taking by
                                 eminent domain, and Tenant shall make no claim
                                 whatsoever against Landlord for damages. Tenant
                                 hereby grants and assigns to Landlord any right
                                 Tenant may now have or hereafter acquire to
                                 such damages to which Landlord is entitled
                                 under this Subsection 13.2 and agrees to
                                 execute and deliver such further instruments of
                                 assignment thereof as Landlord may from time to
                                 time request. Tenant shall, however, have the
                                 right to claim from the condemning authority
                                 all compensation that may be recoverable by
                                 Tenant for damages on account of any loss
                                 incurred by Tenant in removing Tenant's
                                 merchandise, furniture, trade fixtures and
                                 equipment or for damage to Tenant's business;
                                 provided, however, the Tenant may claim such
                                 damages only if they are awarded separately in
                                 the eminent domain proceeding and not as part
                                 of landlord's damages.

14.  TENANT'S DEFAULT.

14.1 Default.                    After ten (10) days' prior written notice to
                                 Tenant, Landlord may at its option pay any
                                 amounts which Tenant is obligated to pay to
                                 third parties pursuant to this Lease, in which
                                 event Tenant shall pay Landlord upon demand.
                                 All amounts in addition to Monthly Base Rent
                                 which Tenant is required to pay under this
                                 Lease shall be considered "additional rent."
                                 The occurrence of any one or more of the
                                 following events shall constitute a default and
                                 breach of this Lease by Tenant.

          (a)  Abandoning the    The abandonment of the Leased Premises by
               Leased Premises   Tenant or the failure of Tenant to be open for
                                 business (except in the event of damage or
                                 destruction to the Leased Premises which
                                 prevents Tenant from conducting any business
                                 thereon or damage to the Leased Premises beyond
                                 Tenant's reasonable control) for more than five
                                 (5) business days.

          (b)  Failure to Pay    The failure by Tenant to make any payment of
               Rent.             Monthly Base Rent, additional rent, or any
                                 other payment required to be made by Tenant
                                 hereunder, as and when due, where such failure
                                 shall continue for a period of ten (10) days
                                 after written notice thereof by Landlord to
                                 Tenant.

          (c)  Failure to        The failure by Tenant to observe or perform any
               Perform.          of the covenants, conditions or provisions of
                                 this Lease to be observed or performed by the
                                 Tenant, other than described in Subsection 14.1
                                 (b) above, where such failure shall continue
                                 for a period of fifteen (15) days after written
                                 notice thereof by Landlord to Tenant; provided,
                                 however, that if the nature of Tenant's default
                                 is such that more than fifteen (15) days are
                                 reasonably required for its cure, then Tenant
                                 shall not be deemed to be in default if Tenant
                                 commences such cure within said fifteen (15)
                                 day period and thereafter diligently prosecutes
                                 such cure to completion.

          (d)  Bankruptcy.       The making by Tenant of any general assignment
                                 or general arrangement for the benefit of
                                 creditors; or the filing by or against Tenant
                                 of a petition to have Tenant adjudged a

                                       11
<PAGE>

                                 bankrupt, or a petition of reorganization or
                                 arrangement under any law relating to
                                 bankruptcy (unless, in the case of a petition
                                 filed against Tenant, the same is dismissed
                                 within sixty (60) days of filing); or the
                                 appointment of a trustee or a receiver to the
                                 possession of substantially all of Tenant's
                                 assets located at or operated from the Leased
                                 Premises or of Tenant's interest in this Lease,
                                 where such seizure is not discharged in thirty
                                 (30) days after appointment of such trustee or
                                 receiver, or the filing of the petition for the
                                 appointment of the same, whichever shall first
                                 occur.

14.2 Remedies in Default.        In the event of any such default or breach by
                                 Tenant, Landlord may at any time thereafter,
                                 with or without notice or demand and without
                                 limiting Landlord in the exercise of a right or
                                 remedy which Landlord may have by reason of
                                 such default or breach:

          (a)  Terminate         Terminate Tenant's right to possession of the
               Lease.            Leased Premises by any lawful means, in which
                                 case this Lease shall terminate and Tenant
                                 shall immediately surrender possession of the
                                 Leased Premises to Landlord. In such event
                                 Landlord shall be entitled to recover from the
                                 Tenant all past due rents to the date of award
                                 by the court having jurisdiction thereof; the
                                 expenses of reletting the Leased Premises,
                                 including necessary renovation and alteration
                                 of the Leased Premises and reasonable
                                 attorneys' fees; the worth at the time of award
                                 by the court having jurisdiction thereof of the
                                 amount by which the unpaid rent called for
                                 herein for the balance of the Term after the
                                 time of such award exceeds the amount of such
                                 loss for the same period that Tenant proves
                                 could be reasonably avoided; and that portion
                                 of any leasing commission paid by Landlord and
                                 applicable to the unexpired Term of this Lease.
                                 Unpaid installments of rent or other sums shall
                                 bear interest from the date due at the rate
                                 provided in Subsection 4.3; or

          (b)  Continue the      Maintain Tenant's right to possession, in which
               Lease.            case this Lease shall continue in effect
                                 whether or not Tenant shall have abandoned the
                                 Leased Premises. In such event Landlord shall
                                 be entitled to enforce all Landlord's rights
                                 and remedies under this Lease, including the
                                 right to recover the Monthly Base Rent and
                                 additional rent as may become due hereunder but
                                 Landlord shall also be required to mitigate its
                                 damages by seeking to re-let the Leased
                                 Premises; or

          (c)  Other Remedies.   Pursue any other remedy now or hereafter
                                 available to Landlord under the laws or
                                 judicial decisions of the State of Oregon.

14.3 Legal Expenses.             If either party is required to bring or
                                 maintain any action (including assertion of any
                                 counterclaim or cross-claim, or claim in a
                                 proceeding in bankruptcy, receivership or any
                                 other proceeding instituted by a party hereto
                                 or by others), or otherwise refers this Lease
                                 to an attorney for the enforcement of any of
                                 the covenants, terms or conditions of this
                                 Lease, the prevailing party in such action
                                 shall, in addition to all other payments
                                 required herein, receive from the other all the
                                 costs incurred by the prevailing party
                                 including reasonable attorneys' fees which the
                                 prevailing party incurred at trial and/or on
                                 any appeal.

                                       12
<PAGE>

14.4 Remedies Cumulative -       Landlord's remedies hereunder are cumulative
     Waiver.                     and the Landlord's exercise of any right or
                                 remedy due to a default or breach by Tenant
                                 shall not be deemed a waiver of, or to alter,
                                 affect or prejudice any right or remedy which
                                 Landlord may have under this Lease or by law.
                                 Neither the acceptance of rent nor any other
                                 acts or omission of Landlord at any time or
                                 times after the happening of any event
                                 authorizing the cancellation or forfeiture of
                                 this Lease, shall operate a waiver of any past
                                 or future violation, breach or failure to keep
                                 or perform any covenant, agreement, term or
                                 condition hereof or to deprive Landlord of its
                                 right to cancel or forfeit this Lease, upon the
                                 written notice provided for herein, at any time
                                 that cause for cancellation or forfeiture may
                                 exist, or be construed so as at any time to
                                 stop Landlord from promptly exercising any
                                 other option, right or remedy that it may have
                                 under any term or provision of this Lease, at
                                 law or in equity.

15.  DEFAULT BY LANDLORD.        Landlord shall not be in default unless
                                 Landlord fails to perform obligations required
                                 of Landlord within thirty (30) days after
                                 written notice by Tenant to Landlord and to the
                                 holder of any mortgage or deed of trust
                                 covering the Leased Premises which describes
                                 the default; provided, however, that if the
                                 nature of Landlord's obligation is such that
                                 more than thirty (30) days are required for
                                 performance, then Landlord shall not be in
                                 default if Landlord commences performance
                                 within such thirty (30) day period and
                                 thereafter diligently prosecutes the same to
                                 completion. Tenant shall provide the holder of
                                 the mortgage or deed of trust with notice and
                                 time to cure as provided in Subsection 17.3.

16.  DAMAGE OR DESTRUCTION.

16.1 Damage and Repair.          In case of damage to the Leased Premises or the
                                 Building by fire or other casualty, Tenant
                                 shall give immediate notice to Landlord. If the
                                 Building is damaged by fire or any other cause
                                 to such extent that the cost of restoration, as
                                 reasonably estimated by Landlord, will equal or
                                 exceed thirty percent (30%) of the replacement
                                 value of the Building (exclusive of
                                 foundations) just prior to the occurrence of
                                 the damage, or if insurance proceeds sufficient
                                 for restoration are for any reason unavailable,
                                 then Landlord may no later than the sixtieth
                                 (60th) day following the damage, give tenant a
                                 notice of election to terminate this Lease. In
                                 the event of such an election this Lease shall
                                 be deemed to terminate on the third (3rd) day
                                 after the giving of said notice, and Tenant
                                 shall surrender possession of the Leased
                                 Premises within a reasonable time thereafter,
                                 and the Monthly Base Rent shall be apportioned
                                 as of the date of said surrender and any rent
                                 paid for any period beyond said date shall be
                                 repaid to Tenant. If the cost of restoration as
                                 estimated by Landlord shall amount to less than
                                 thirty percent (30%) of such replacement value
                                 of the Building and insurance proceeds
                                 sufficient for restoration are available, or if
                                 despite the cost Landlord does not elect to
                                 terminate this Lease, Landlord shall restore
                                 the Building and the Leased Premises (to the
                                 extent of improvements to the Leased Premises
                                 originally provided by Landlord hereunder) with
                                 reasonable promptness, subject to delays beyond
                                 Landlord's control and delays in the making of
                                 insurance adjustments by Landlord, and Tenant
                                 shall have no right to terminate this Lease
                                 except as herein provided. To the extent that
                                 the

                                       13
<PAGE>

                                 Premises are rendered untenantable, the rent
                                 shall proportionately abate, except in the
                                 event such damage resulted or was contributed
                                 to directly or indirectly from the act, fault
                                 or neglect of Tenant, Tenant's officers,
                                 contractors, agents, employees, invitees or
                                 licensees, in which event rent shall abate only
                                 to the extent Landlord receives proceeds from
                                 Landlord's rental income Insurance policy to
                                 compensate Landlord for loss of rent.

16.2 Destruction During Last     In case the Building shall be substantially
     Year of Term.               destroyed by fire or other cause at any time
                                 during the last twenty-four (24) calendar
                                 months of the Term or of any extensions or
                                 renewals thereof, either Landlord or Tenant may
                                 terminate this Lease upon written notice to the
                                 other party hereto given within sixty (60) days
                                 of the date of such destruction.

16.3 Business Interruption.      No damages, compensation or claim shall be
                                 payable by Landlord for inconvenience, loss of
                                 business or annoyance arising from any repair
                                 or restoration of any portion of the Leased
                                 Premises or of the Building. Landlord shall use
                                 its best efforts to effect such repairs
                                 promptly.

16.4 Tenant Improvements.        Landlord will not carry insurance of any kind
                                 on any improvements paid for by Tenant or on
                                 Tenant's furniture or furnishings or on any
                                 fixtures, equipment, improvements or
                                 appurtenances of Tenant under this Lease, and
                                 Landlord shall not be obligated to repair any
                                 damage thereto or replace the same.

16.5 Express Agreement.          The provisions of this Section shall be
                                 considered an express agreement governing any
                                 case of damage or destruction of the Building
                                 or Leased Premises by fire or other casualty.

17.  SUBORDINATION AND
     ATTORNMENT: MORTGAGEE
     PROTECTION.

17.1 Subordination.              This Lease shall be subordinate to any existing
                                 or future mortgages or deeds of trust on the
                                 Building or on the leasehold interest held by
                                 Landlord, and to any extensions, renewals, or
                                 replacements thereof; provided, that the
                                 mortgagee or beneficiary, as the case may be,
                                 shall agree, in exchange for the agreement of
                                 Tenant to attorn to such mortgagee or
                                 beneficiary, to recognize this Lease in the
                                 event of foreclosure if Tenant is not in
                                 default at such time. At the request of
                                 Landlord, Tenant shall promptly execute and
                                 deliver all instruments which may be
                                 appropriate to further secure and document such
                                 subordination.

17.2 Tenant's Certificate.       Tenant shall at any time and from time to time
                                 upon not less than twenty (20) days' prior
                                 written notice from Landlord execute,
                                 acknowledge and deliver to Landlord a statement
                                 in writing (a) certifying that this Lease is
                                 unmodified and in full force and effect (or, if
                                 modified, stating the nature of such
                                 modification and certifying that this Lease as
                                 so modified is in full force and effect), and
                                 the date to which the rental and other charges
                                 are paid in advance, if any, and (b)
                                 acknowledging that there are not, to Tenant's
                                 knowledge, any uncured defaults on the part of
                                 the Landlord hereunder, or specifying such
                                 defaults if any are claimed, and (c) setting
                                 forth the date of commencement of rents and
                                 expiration of the Term hereof. Any such
                                 statement may be

                                       14
<PAGE>

                                 relied upon by any prospective purchaser or
                                 encumbrancer of all or any portion of the
                                 Building.

17.3 Mortgagee Protection        Tenant agrees to give any mortgagees or deed of
     Clause.                     trust holders, by registered or certified mail,
                                 a copy of any notice of default served upon the
                                 Landlord, provided that prior to such notice
                                 Tenant has been notified in writing of the
                                 addresses of such mortgagees or deed of trust
                                 holders. Notwithstanding anything to the
                                 contrary in this Lease, the Landlord shall not
                                 be in default under any provision of this Lease
                                 unless written notice specifying such default
                                 is given to Landlord and to all persons who
                                 have an interest in all or part of the Building
                                 as mortgagee and/or deed of trust beneficiary,
                                 and the provisions of Section 15 have been
                                 complied with. Tenant further agrees as
                                 follows: (i) if Landlord fails to cure or
                                 commence the cure of such default within the
                                 time period allowed under Section 15, above,
                                 then a mortgagee or deed of trust beneficiary
                                 shall have an additional thirty (30) days
                                 within which to cure such default; and (ii) if
                                 such default cannot be cured within that time,
                                 then a mortgagee or deed of trust beneficiary
                                 shall have such additional time as may be
                                 necessary if within such additional thirty (30)
                                 days any mortgagee or deed of trust beneficiary
                                 has commenced and is diligently pursuing the
                                 remedies necessary to cure such default
                                 (including but not limited to commencement of
                                 foreclosure proceedings if necessary to affect
                                 such cure), in which event this Lease shall not
                                 be terminated if such remedies are being so
                                 diligently pursued.

18.  ACCESS BY LANDLORD.         Landlord or Landlord's employees, agents, and
                                 contractors shall have the right to enter the
                                 Leased Premises with reasonable notice to
                                 examine the same or to make such repairs,
                                 alterations, improvements or additions as
                                 Landlord may deem necessary or desirable. If
                                 Tenant is not personally present to permit
                                 entry and an entry is necessary, Landlord may
                                 in case of emergency forcibly enter the same,
                                 without rendering Landlord liable therefor.
                                 Nothing contained herein shall be construed to
                                 impose upon Landlord any duty of repair of the
                                 Leased Premises or Building except as otherwise
                                 specifically provided for herein.

19.  SURRENDER OR ABANDONMENT
     OF LEASED PREMISES.

19.1 Surrender of Possession.    Tenant shall promptly yield and deliver to
                                 Landlord possession of the Leased Premises at
                                 the expiration or prior termination of this
                                 Lease. Landlord may place and maintain a "For
                                 Rent" sign in conspicuous places on the Leased
                                 Premises for sixty (60) days prior to the
                                 expiration or prior termination of this Lease.

19.2 Holding Over.               Any holding over by Tenant after the expiration
                                 of the Term hereof, with Landlord's consent
                                 shall be construed to be a tenancy from
                                 month-to-month at the rents and on all of the
                                 terms and conditions set forth herein, to the
                                 extent not inconsistent with a month-to-month
                                 tenancy; provided, however, the Monthly Base
                                 Rent, at Landlord's discretion shall equal up
                                 to one hundred fifty percent (150%) of the
                                 Monthly Base Rent in effect immediately prior
                                 to such month-to-month tenancy.

                                       15
<PAGE>

19.3 Abandonment.                Should Tenant abandon the Leased Premises or be
                                 dispossessed by process of law or otherwise for
                                 more than five (5) business days, such
                                 abandonment, vacation or dispossession shall be
                                 deemed a breach of this Lease, and, in addition
                                 to any other rights which Landlord may have,
                                 Landlord may remove any personal property
                                 belonging to Tenant which remains on the Leased
                                 Premises and store the same, the cost of such
                                 removal and storage to be charged to the
                                 account of Tenant.

19.4 Voluntary Surrender.        The voluntary or other surrender of this Lease
                                 by Tenant, or a mutual cancellation thereof,
                                 shall not work a merger, but shall, at the
                                 option of Landlord, terminate all or any
                                 existing subleases or subtenancies, or operate
                                 as an assignment to it of any or all such
                                 subleases or subtenancies.

20.  QUIET ENJOYMENT.            Tenant, upon fully complying with and promptly
                                 performing all of the terms, covenants and
                                 conditions of this Lease on its part to be
                                 performed, and upon the prompt and timely
                                 payment of all sums due hereunder, shall have
                                 and quietly enjoy the Leased Premises for the
                                 Term set forth herein as against any adverse
                                 claim of Landlord or any party claiming under
                                 Landlord.

21   AUTHORITY OF PARTIES.       If Tenant is a corporation, each individual
                                 executing this Lease on behalf of such
                                 corporation represents and warrants that he is
                                 duly authorized to execute and deliver this
                                 Lease on behalf of said corporation, in
                                 accordance with a duly adopted resolution of
                                 the board of directors of such corporation,
                                 that such action and execution is in accordance
                                 with the bylaws of such corporation, and that
                                 this Lease is binding upon such corporation in
                                 accordance with its terms. Tenant has
                                 designated the person named in Section 1.1 as
                                 Tenant's Representative. Landlord may rely on
                                 all communications and statements of the
                                 Tenant's Representative as the authorized
                                 communications and statements of Tenant. Tenant
                                 may notify Landlord that another individual is
                                 the Tenant's Representative and Landlord may
                                 rely on the communications and statements of
                                 such individual.

22.  SIGNS.                      Tenant shall not place or suffer to be placed
                                 on the exterior walls of the Leased Premises or
                                 upon the roof or any exterior door or wall or
                                 on the exterior or interior of any window
                                 thereof any sign, awning, canopy, marquee,
                                 advertising matter, decoration, letter or other
                                 thing of any kind (exclusive of the signs, if
                                 any, which may be provided for in the original
                                 construction or improvement plans and
                                 specifications approved by the Landlord or
                                 Tenant hereunder), without the prior written
                                 consent of Landlord.

23.  MISCELLANEOUS.

23.1 Tenant Defined.             The word "Tenant" as used herein shall mean
                                 each and every person, partnership or
                                 corporation who is mentioned as a Tenant herein
                                 or who executes this Lease as Tenant.

23.2 Broker's Commission.        Tenant represents and warrants that it has
                                 incurred no liabilities or claims for brokerage
                                 commissions or finder's fees in connection with
                                 the execution of this Lease and that it has not
                                 dealt with or has any knowledge of any real
                                 estate broker, agent or salesperson in
                                 connection with this Lease except the Broker
                                 whose name is set forth in Subsection 1.1.

                                       16
<PAGE>

                                 Tenant agrees to indemnify and hold Landlord
                                 harmless from all such liabilities or claims
                                 (including, without limitation, attorneys'
                                 fees).

23.3 Partial Invalidity.         If any term, covenant, or condition of this
                                 Lease or the application thereof to any person
                                 or circumstances is, to any extent, invalid or
                                 unenforceable, the remainder of this Lease, or
                                 the application of such term, covenant or
                                 condition to persons or circumstances other
                                 than those as to which it is held invalid or
                                 unenforceable, shall not be affected thereby
                                 and each term, covenant or condition of this
                                 Lease shall be valid and be enforced to the
                                 fullest extent permitted by law.

23.4 Recording.                  Tenant shall not record this Lease without the
                                 prior written consent of Landlord. However,
                                 upon the request of Landlord or Tenant, both
                                 parties shall execute a memorandum of "short
                                 form" of this Lease for the purposes of
                                 recordation in a form customarily used for such
                                 purposes. Said memorandum or short form of this
                                 Lease shall describe the parties, the Leased
                                 Premises and the Term and shall incorporate
                                 this Lease by reference.

23.5 Notices.                    Any notice required in accordance with any of
                                 the provisions herein if to Landlord shall be
                                 delivered or mailed by registered or certified
                                 mail to the address of Landlord as set forth by
                                 the signature of the Parties, or at such other
                                 place as Landlord may in writing from time to
                                 time direct to Tenant, and if to Tenant, shall
                                 be delivered or mailed by registered or
                                 certified mail to Tenant at the Leased Premises
                                 or at such other place as Tenant may in writing
                                 from time to time direct to Landlord. If there
                                 is more than one Tenant, any notice required or
                                 permitted hereunder may be given by or to any
                                 one thereof, and shall have the same force and
                                 effect as if given by or to all thereof.

23.6 Waiver.                     The waiver by Landlord or Tenant of any term,
                                 covenant or condition herein contained shall
                                 not be deemed to be a waiver of such term,
                                 covenant or condition or any subsequent breach
                                 of the same or any other term, covenant or
                                 condition herein contained. The subsequent
                                 acceptance of Monthly Base Rent, additional
                                 rent or sum hereunder by Landlord shall not be
                                 deemed to be a waiver of any preceding default
                                 by Tenant of any term, covenant or condition of
                                 this Lease, regardless of Landlord's knowledge
                                 of such preceding default at the time of the
                                 acceptance of such sum.

23.7 Joint Obligation.           If there is more than one Tenant, the
                                 obligations hereunder imposed shall be joint
                                 and several.

23.8 Time.                       Time is of the essence of this Lease and each
                                 and all of its provisions in which performance
                                 is a factor.

23.9 Successors and Assigns.     All the terms, conditions, covenants and
                                 agreements of this Lease shall extend to and be
                                 binding upon Landlord, Tenant and their
                                 respective heirs, administrators, executors,
                                 successors and assigns, and upon any person or
                                 persons coming into ownership or possession of
                                 any interest in the Leased Premises by
                                 operation of law or otherwise, and shall be
                                 construed as covenants running with the land.

                                       17
<PAGE>

23.10 Prior Agreements.          This Lease contains all of the agreements of
                                 the parties hereto with respect to any matter
                                 covered or mentioned in this Lease, and no
                                 prior agreements or understanding pertaining to
                                 any such matters shall be effective for any
                                 purpose. No provisions of this Lease may be
                                 amended or added to except by an agreement in
                                 writing signed by the parties hereto or their
                                 respective successors in interest. This Lease
                                 shall not be effective or binding on any party
                                 until fully executed by both parties hereto.

23.11 Choice of Law.             This Lease shall be governed by the laws of the
                                 State of Oregon.

IN WITNESS WHEREOF, the parties hereto have executed this instrument the day and
year first above set forth.

LANDLORD:                            TENANT:
--------                             --------

ALCO INVESTMENT COMPANY              ADVANCED TELECOMMUNICATIONS, INC.

By:  /s/ Douglas C. Rosen            By:  /s/ Satish C. Timari
   ------------------------------       ------------------------------
   Douglas C. Rosen                     (Print Name)  Satish C. Timari
   Its Secretary                        Its Vice President, Engg. & Net Imptn.

Address:  921 SW Washington,         Address:  730 Second Avenue South,
          Suite 100                            Ste 1200
          Portland, OR 97205                   Minneapolis MN 55402

                                       18
<PAGE>

  [STATE     MICHELE J. SPERENZA
   SEAL      Notary Public
    OF       Ramsey County-Minnesota
MINNESOTA]   My Commission Expires Jan. 31, 2000

STATE OF MINNESOTA )
                   ) SS
COUNTY OF HENNEPIN )

The forgoing instrument was acknowledged before me this 22 day of November,
1999, by Satish Tiwari, the Vice-President/Engineering and Network
Implementation of ADVANCED TELECOMMUNICATIONS, INC., a Delaware corporation, on
behalf of the corporation.

/s/            Michele J. Sperenza
------------------------------------------
Notary Public
<PAGE>

STATE OF:  OREGON          }
                           } ss.
COUNTY OF:  Multnomah      }

I certify that I know or have satisfactory evidence that Douglas C. Rosen signed
this instrument, on oath stated that he was authorized to execute the
instrument, and acknowledged it as the Secretary of Alco Investment Company to
be free and voluntary act of such corporation for the uses and purposes
mentioned in the instrument.

[OREGON   OFFICIAL SEAL                     Dated:       11/23/99
STATE     JULIA A SPILKER                   Before me: /s/ Julia A. Spilker
SEAL]     NOTARY PUBLIC-OREGON              Notary Public for: Oregon
          COMMISSION NO. 317305             My commission expires 12/20/02
          COMMISSION EXPIRES DEC. 20, 2002

STATE OF: _________________________________________}
                                                   }  ss.
COUNTY OF:_________________________________________}

I certify that I know or have satisfactory evidence that
____________________________ signed this instrument, on oath stated that he/she
was authorized to execute the instrument, and acknowledged it as the
__________________________________________________________ of Advanced
Telecommunications, Inc. to be free and voluntary act of such corporation for
the uses and purposes mentioned in the instrument.

                                            Dated: ____________________________
                                            Before me: ________________________
                                            Notary Public for _________________
                                            My commission expires:_____________
<PAGE>

                                   EXHIBIT A

                                       TO

                              PITTOCK BLOCK LEASE

                         Legal Description of Building

Lots 1 through 8 inclusive, Block 215, CITY OF PORTLAND, in the City of
Portland, County of Multnomah and State of Oregon.
<PAGE>

                                      THE
                                    PITTOCK
                                     BLOCK

                                   EXHIBIT B

   [GRAPHIC OMITTED - FLOOR PLAN OF FOURTH FLOOR DESIGNATING LEASED PREMISES]
<PAGE>

                                    Addendum
                                       To
                              Pittock Block Lease

                              Base Rent Escalation

     This Addendum to the Pittock Block Lease is entered into between the
Landlord and Tenant executing this Addendum for the purpose of amending such
Lease as provided herein.

     1. On the first anniversary of the Commencement Date and on each
anniversary date thereafter during the Lease Term, (the "Escalation Dates"), the
Base Rent shall be increased by the Percentage Increase, if any. The "Percentage
Increase" shall mean the percentage increase, if any, in the United States
Consumer Price Index (as revised), All Urban Consumers, All Items, West-A (Base:
1982-1984 = 100), as published or issued by the United States Department of
Labor, Bureau of Labor Statistics (the "CPI Index"), computed from the Base Date
to the Comparison Date, as defined below. The "Comparison Date" shall mean the
date on which the most recent Index figure was published or issued prior to the
subject Escalation Date. The "Base Date" shall mean the date on which the most
recent Index figure was published prior to the Commencement Date. If the
Comparison Date precedes the subject Escalation Date by more than four (4)
calendar months, the CPI Index shall be deemed "no longer published or issued,"
and a substitute index or procedure shall be used as provided below. If at any
time prior to the subject Escalation Date the Index is no longer published or
issued, the parties shall use a substitute index, if available, or a substitute
procedure, to determine the "Percentage Increase" which accurately reflects the
increase in prices in a representative sample of consumer goods and services in
major expenditure groups, such as food, housing, apparel, transportation, health
and recreation, in the Portland, Oregon metropolitan area from the Base Date to
the Comparison Date. If the parties are unable to agree, within thirty (30) days
after demand of one (1) party on the selection of a substitute index or
procedure to replace the CPI Index, or if there is a dispute with respect to the
computation of any rental adjustment as herein provided, the selection or
computation shall be made by arbitration pursuant to Section 2 of this Addendum.

     2. If any controversy, claim or dispute arises in connection with any
provision of this Addendum which expressly provides for resolution thereof by
arbitration pursuant to the terms of this Section 2, the same shall be submitted
to arbitration at the offices of the American Arbitration Association ("AAA") in
Portland, Oregon before a single arbitrator pursuant to the Commercial
Arbitration Rules of the AAA. If the AAA is not then functioning, the
arbitration shall be conducted in accordance with the requirements of O.R.S.
33.210-.340, and, if the parties are unable to agree upon an arbitrator within
ten (10) days of one party's notice of demand for arbitration to the other,
either party may petition the Presiding Judge of Multnomah County Circuit Court
to appoint the arbitrator. The arbitrator appointed by the AAA or the Presiding
Judge of Multnomah County Circuit Court shall be a person who has substantial
experience in the Portland, Oregon area in the professional area which is at
issue in the arbitration. Whether arbitration is conducted pursuant to the
Commercial Arbitration Rules of the AAA or O.R.S. 33.210-.340, the arbitrator
shall endeavor to promptly conduct and conclude the arbitration hearing within
sixty (60) days of his appointment. The arbitrator shall render his decision
within twenty (20) days of the conclusion of the arbitration hearing. The
decision of the arbitrator shall be final and binding upon the parties and shall
constitute a final adjudication of all matters submitted to arbitration. A
judgment on the arbitrator's award may be entered in Multnomah County Circuit
court and enforced as if the award were a judgment of such court.

     3. Except as expressly provided herein, all other provisions of the Lease
and the Exhibits and Addenda thereto shall remain as set forth therein. In the
event of a conflict between this Addendum and the Lease proper, the provisions
of this Addendum shall prevail.

LANDLORD:                            TENANT:
--------                             --------

ALCO INVESTMENT COMPANY              ADVANCED TELECOMMUNICATIONS, INC.

By:  /s/ Douglas C. Rosen            By:  /s/ Satish C. Timari
   ------------------------------       ------------------------------
   Douglas C. Rosen                     (Print Name)  Satish C. Timari
   Its Secretary                        Its Vice President, Engg. & Net Imptn.
<PAGE>

                                    Addendum
                                       To
                              Pittock Block Lease

                            Market Rental Adjustment

     This Addendum to the Pittock Block Lease is entered into between the
Landlord and Tenant executing this Addendum for the purpose of amending such
Lease as provided herein.

     At the beginning of the sixth year of the Lease Term the Monthly Base Rent
for the Leased Premises shall be adjusted to the then Market Rental of the
Building. The Market Rental shall be specified by the Landlord sixty (60) days
in advance of the adjustment date and shall be the then current monthly rental
rate being offered by Landlord to other telecommunication companies in the
Building. In no event shall the Market Rental be less than the Base Rent
established by Landlord in its most recent lease agreement prior to the
adjustment date with a third party telecommunications tenant in the Building.

     If the parties are still in disagreement twenty (20) days after delivery of
such notice from Landlord to Tenant, Landlord and Tenant shall immediately
choose an M.A.I. appraiser who shall determine the Market Rental for the
Premises as provided herein. If Landlord and Tenant are unable to agree on the
selection of an appraiser, either party may petition the Presiding Judge of
Multnomah County Circuit Court who shall select the appraiser. Until the Market
Rental is determined as provided herein, the Tenant shall pay Base Rent based on
the Market Rental specified by the Landlord, and if the Market Rental is
subsequently determined to be different than the Market Rental specified by the
Landlord, the Landlord or Tenant, as the case may be, shall reimburse the other
for such difference.

     2. Except as expressly provided herein, all other provisions of the Lease
and the Exhibits and Addenda thereto, shall remain as set forth therein. In the
event of a conflict between this Addendum and the Lease proper, the provisions
of the Addendum shall prevail.

LANDLORD:                            TENANT:
--------                             --------

ALCO INVESTMENT COMPANY              ADVANCED TELECOMMUNICATIONS, INC.

By:  /s/ Douglas C. Rosen            By:  /s/ Satish C. Timari
   ------------------------------       ------------------------------
   Douglas C. Rosen                     (Print Name)  Satish C. Timari
   Its Secretary                        Its Vice President, Engg. & Net Imptn.
<PAGE>

                                    Addendum
                                       To
                              Pittock Block Lease

                          Cooling Tower Connection Fee

     This Addendum to the Pittock Block Lease is entered into between the
Landlord and Tenant executing this Addendum for the purpose of amending such
Lease as provided herein.

     Tenant shall have the right and hereby agrees to connect forty-five (45)
tons of capacity to Landlord's common cooling tower system to serve Tenant's air
conditioning equipment in the Leased Premises subject to the following
provisions:

          1. The one time connection fee is forty-five thousand dollars
     ($45,000.00), payable to Landlord within 30 days of the connection or
     within six months of the Commencement Date of the Lease Term, whichever
     occurs first.

          2. In addition to the connection fee, all engineering, permits and
     installation costs shall be at Tenant's expense. Tenant shall not make any
     connection to Landlord's common cooling tower system without Landlord's
     prior written approval of engineering and installation specifications,
     which consent is subject to such conditions and building standards as
     Landlord deems reasonably appropriate.

          3. In addition to Monthly Base Rent, Other Charges and all other
     amounts due from Tenant under this Lease, Tenant shall pay its pro rata
     share of all costs and expenses associated with the cooling tower system,
     including but not limited to chemical treatment, maintenance, repair and
     replacement expenses. Tenant's pro rata share for purposes of this section
     shall be based on the connected load of Tenant compared to the total
     connected capacity of the cooling tower system. Payment must be made within
     ten days of receipt of invoice.

Except as expressly provided herein, all other provisions of the Lease and the
Exhibits and Addenda thereto, shall remain as set forth therein. In the event of
a conflict between this Addendum and the Lease proper, the provisions of the
Addendum shall prevail.

LANDLORD:                            TENANT:
--------                             --------

ALCO INVESTMENT COMPANY              ADVANCED TELECOMMUNICATIONS, INC.

By:  /s/ Douglas C. Rosen            By:  /s/ Satish C. Timari
   ------------------------------       ------------------------------
   Douglas C. Rosen                     (Print Name)  Satish C. Timari
   Its Secretary                        Its Vice President, Engg. & Net Imptn.
<PAGE>

                                    Addendum
                                       To
                              Pittock Block Lease

                       Primary Electrical Connection Fee

     This Addendum to the Pittock Block Lease is entered into between the
Landlord and Tenant executing this Addendum for the purpose of amending such
Lease as provided herein.

     Tenant shall have the right and hereby agrees to connect 600 amps at 480
volt electrical service capacity to Landlord's common system, subject to the
following provisions:

          1. The one time connection fee one hundred thirty-five thousand
     dollars ($135,000.00), payable to Landlord within 30 days of the connection
     or within six months of the Commencement Date of the Lease Term, whichever
     occurs first.

          2. In addition to the connection fee, all engineering, permits,
     installation and connection costs shall be at Tenant's expense. Tenant
     shall not make any connection to Landlord's common electrical system
     without Landlord's prior written approval of engineering and installation
     specifications, which consent is subject to such conditions and building
     standards as Landlord deems appropriate.

          3. In addition to Monthly Base Rent, Other Charges and all other
     amounts due from Tenant under this Lease, Tenant shall pay its pro rata
     share of all costs and expenses associated with the electrical system,
     including but not limited to maintenance, repair and replacement expenses.
     Tenant's pro rata share for purposes of this section shall be based on the
     connected load of Tenant compared to the total connected capacity of the
     electrical system. Payment must be made within ten days of receipt of
     invoice.

     Except as expressly provided herein, all other provisions of the Lease and
the Exhibits and Addenda thereto, shall remain as set forth therein. In the
event of a conflict between this Addendum and the Lease proper, the provisions
of the Addendum shall prevail.

LANDLORD:                            TENANT:
--------                             --------

ALCO INVESTMENT COMPANY              ADVANCED TELECOMMUNICATIONS, INC.

By:  /s/ Douglas C. Rosen            By:  /s/ Satish C. Timari
   ------------------------------       ------------------------------
   Douglas C. Rosen                     (Print Name)  Satish C. Timari
   Its Secretary                        Its Vice President, Engg. & Net Imptn.
<PAGE>

                                    Addendum
                                       To
                              Pittock Block Lease

                       Emergency Generator Connection Fee

     This Addendum to the Pittock Block Lease is entered into between the
Landlord and Tenant executing this Addendum for the purpose of amending such
Lease as provided herein.

     Tenant shall have the right and hereby agrees to connect 400 amps at 480
volt three phase emergency generator service capacity to Landlord's common
system, subject to the following provisions:

     1. The one time connection fee is four hundred thousand dollars
($400,000.00). Tenant has elected to make an initial payment of one hundred two
thousand, five hundred dollars ($102,500.00) at the time of connection which the
parties agree with occur on July 1, 2000. The remaining balance of the
connection fee is two hundred ninety-seven thousand, five hundred dollars
($297,500.00) and shall be fully amortized over forty-two (42) months at the
annualized interest rate of ten percent (10.0%). Therefore, in addition to the
initial connection fee of one hundred two thousand, five hundred dollars
($102,500.00), the Monthly Base Rent and all other amounts due under the Lease,
Tenant shall pay as additional Monthly Base Rent the amount of six thousand,
eight hundred sixty-four dollars ($6,864.00) per month commencing on July 1,
2000 and continuing each month thereafter until December 1, 2003.

     2. In addition to the connection fee, all engineering, permits,
installation and connection costs shall be at Tenant's expense. Tenant shall not
make any connection to Landlord's common emergency generator system without
Landlord's prior written approval of engineering and installation
specifications, which consent is subject to such conditions and building
standards as Landlord deems reasonably appropriate.

     3. In addition to Monthly Base Rent, Other Charges and all other amounts
due from Tenant under this Lease, Tenant shall pay its pro rata share of all
costs and expenses associated with the emergency generator system, including but
not limited to maintenance, repair and replacement expenses. Tenant's pro rata
share for purposes of this section shall be based on the connected load of
Tenant compared to the total connected capacity of the emergency generator
system. Payment must be made within 30 days of receipt of invoice.

     Except as expressly provided herein, all other provisions of the Lease and
the Exhibits and Addenda thereto, shall remain as set forth therein. In the
event of a conflict between this Addendum and the Lease proper, the provisions
of the Addendum shall prevail.

LANDLORD:                            TENANT:
--------                             --------

ALCO INVESTMENT COMPANY              ADVANCED TELECOMMUNICATIONS, INC.

By:  /s/ Douglas C. Rosen            By:  /s/ Satish C. Timari
   ------------------------------       ------------------------------
   Douglas C. Rosen                     (Print Name)  Satish C. Timari
   Its Secretary                        Its Vice President, Engineering &
                                        Network Implementation
<PAGE>

                                    Addendum
                                       To
                              Pittock Block Lease

                               Connectivity Right

This Addendum to the Pittock Block Lease is entered into between the Landlord
and Tenant executing this Addendum for the purpose of amending such Lease as
provided herein.

     1. Cross Connect Facility. Tenant shall have the right to share usage of
     Landlord's common telecommunication Cross Connect Facility ("CCF') only in
     accordance with the following provisions:

               a. All cabling shall be provided by Tenant at Tenant's expense.
          Landlord shall supervise the maintenance and use of the CCF.

               b. Tenant shall abide by the regulations, specifications and
          standards established by Landlord from time to time governing the use
          of the CCF.

               c. Tenant shall pay cross connect fees to Landlord pursuant to
          the following schedule:

                                                 Copper CCF  Fiber CCF
                                                 ----------  --------
                 One time entry fee:             $1000.00    $1000.00
                 One time per panel fee:           375.00      200.00
                 Monthly per panel fee:             75.00      100.00

                 (1)  The above fees are based on Landlord's current building
                 standard equipment schedule with the following cross
                 connect capacities:

                             DS1 cross connect panels are 56 position
                             DS3 cross connect panels are 24 position
                             Fiber cross connect panels are 6 fiber

                 In the event Landlord changes the building standard
                 equipment specification, the monthly panel fee shall be
                 modified, if necessary, to maintain the same fee per
                 position.

               d. Cross connect fees shall be adjusted to Landlord's then rates
          in the Building at the beginning of the sixth year of the Lease Term
          and at each renewal option period, but shall in no event be less than
          the greater of (i) the amounts set forth above, or (ii) the amounts
          determined in any previous adjustment.

     2. Cabling Right of Way. Landlord gives Tenant the right of way to install
     cable from the Leased Premises to the Cross Connect Facility subject to the
     following provisions:

          a. Such installation is at Tenant's expense and subject to the
          regulations, specifications and standards established by Landlord.

          b. Such installation must be coordinated with and approved by the
          Pittock Block Building engineer.

          c. Tenant shall pay its pro rata share of common conduit attachment
          structures or pathway improvements provided by Landlord.

3. Direct Tenant to Tenant Connection Not Allowed. Tenant is not allowed to make
or accept direct connections to other telecommunication, internet and present or
future equivalent tenants' Leased Premises within the Building. All connections
between telecommunications tenants within the Building must occur in the CCF as
defined above.
<PAGE>

Page Two
Connectivity Right Addendum

Except as expressly provided herein, all other provisions of the Lease and the
Exhibits and other Addenda thereto shall remain as set forth therein. In the
event of a conflict between this Addendum and the Lease proper, the provisions
of this Addendum shall prevail.

LANDLORD:                            TENANT:
--------                             --------

ALCO INVESTMENT COMPANY              ADVANCED TELECOMMUNICATIONS, INC.

By:  /s/ Douglas C. Rosen            By:  /s/ Satish C. Timari
   ------------------------------       ------------------------------
   Douglas C. Rosen                     (Print Name)  Satish C. Timari
   Its Secretary                        Its Vice President, Engineering &
                                        Network Implementation
<PAGE>

                                    ADDENDUM
                                       TO
                              PITTOCK BLOCK LEASE

                             RULES AND REGULATIONS

1. No sign, placard, picture, advertisement, name or notice shall be posted or
affixed on or to any part of the outside of the Building or the Premises without
the prior written consent of Landlord, and Landlord shall have the right to
remove any sign, placard, picture, advertisement, name or notice posted in
violation of this rule, without notice to and at the expense of Tenant.

2. The directory of the Building will be provided exclusively for the display of
the name and location of tenants and Landlord reserves the right to exclude any
other names therefrom. Landlord reserves the right to restrict the amount of
directory space utilized by any Tenant.

3. The sidewalks, halls, passages, exits, entrances, elevators and stairways
shall not be obstructed by any Tenant or used for any purpose other than for
ingress and egress from the Premises. The halls, passages, exits, entrances,
elevators, stairways, balconies and roof are not for the use of the general
public and the Landlord shall in all cases retain the right to control and
prevent access thereto by all persons whose presence in the judgement of the
Landlord shall be prejudicial to the safety, character, reputation and interests
of the Building and its tenants. No Tenant and no employees, invitees or
licensees of any Tenant shall enter the mechanical rooms, electrical closets,
janitorial closets, or similar area or go upon the roof of the Building without
the prior written consent of the Landlord.

4. The Landlord shall designate appropriate entrances and a "freight" elevator
for deliveries or other movement to or from the Premises of equipment,
materials, supplies, furniture and other bulky or heavy articles, and Tenant
shall not use any other entrances or elevators for such purposes. The freight
elevator shall be available for use by Tenants in the building, subject to such
reasonable scheduling as Landlord in its discretion shall deem appropriate. All
means or methods used to move equipment, materials, supplies, furniture or other
property in or out of the Building must be approved by Landlord prior to any
such movement. All floors must be properly protected including hallway, lobby
and elevator carpet. Landlord will not be responsible for loss of or damage to
any property during movement into or out of the Building or Premises, and all
damage to the Building during the course of moving any article of Tenant's
property shall be repaired at the expense of Tenant. Tenant shall move all
freight, supplies, furniture, fixtures and other personal property only at such
times as may be designed by Landlord. Unattended vehicles will be towed at the
owner's expense.

5. Tenant shall not place or keep furniture or other items on the terraces or
roof of the Building without first obtaining the written approval of the
Landlord. Tenant shall not place any item of any nature on any window sill.

6. Landlord reserves the right to exclude from the building between the hours of
5:30 p.m. and 7:00 a.m. and at all hours on Saturdays, Sundays and legal
holidays all persons who do not present identification acceptable to Landlord.
Each Tenant shall provide Landlord with a list of all persons authorized by
Tenant to enter its Premises and shall be liable to Landlord for any loss or
injury to the property of the Landlord or other tenants caused by such persons.
Landlord shall in no case be liable to anyone for any error with regard to the
admission to or exclusion from the Building of any person. In the case of
invasion, mob, riot, public excitement or other circumstances rendering such
action advisable in Landlord's opinion, Landlord reserves the right to prevent
access to the Building during the continuance of the same by such action as
Landlord may deem appropriate, including closing doors.

7. The restrooms and the fixtures and equipment contained therein shall not
be used for any purpose other than that for which they were constructed.
Restroom fixtures shall not be used for the disposal of foreign substances
(e.g. coffee grounds) and the expense of any
<PAGE>

breakage, stoppage or damage resulting from violation of this rule shall be
borne by the responsible Tenant.

8. Except with the prior written consent of Landlord, no person other than those
employed by Landlord shall be permitted to enter the Building for the purpose of
cleaning the same or providing janitorial services. Tenant shall exercise due
care to preserve the good order and cleanliness of the Premises.

9. Tenant shall not permit the Premises to be occupied or used in a manner
offensive or objectionable to the other occupants of the building, persons
having business therein, or the occupants of neighboring buildings.
Specifically, tenants shall not use, keep or permit to be used or kept any
noxious gas or odorous substance in the Premises. Tenant shall not allow any
animals of any kind to be brought into or kept in or about the Premises of the
Building. Tenant shall not make or permit to be made any loud or disturbing
noises, whether by any musical instrument, radio, phonograph, appliance, or in
any other way. Tenant shall not install any radio or television antenna,
loudspeaker, or other device on the roof or exterior walls or windows of the
Building.

10. Tenants shall not use or keep in the Premises or the Building any kerosene,
gasoline, combustible fluid, toxic chemical, radioactive substance or other
dangerous material.

11. Tenant shall not disturb, solicit, or canvass any occupant of the
building and shall cooperate to prevent same.

12. All keys to offices, rooms and restrooms shall be obtained from Landlord's
building management office. Tenant shall not duplicate keys or have keys made.
Tenant, upon termination of the tenancy, shall deliver to the Landlord all keys
which shall have been furnished to Tenant by the Landlord. In the event that
Tenant or Tenant's employees or visitors lose a key, Tenant shall pay Landlord
the cost of replacing same or of changing the lock or locks opened by such lost
key if Landlord deems it necessary to make such change.

13. Tenant shall not lay linoleum, tile, carpet or other similar floor covering
so that the same shall be affixed to any floor of the Premises in any manner
except as approved by the Landlord. The expense of repairing any damage
resulting from a violation of this rule or of removing any floor coverings
affixed in violation of this rule shall be borne by the Tenant.

14. Before leaving the Building, Tenant and Tenant's employees shall (1) see
that the doors of the Premises are closed and securely locked; (2) shut off all
water faucets and water-using appliances so as to prevent waste or damage.
Tenant shall indemnify the Landlord and other tenants for any injuries sustained
by any of them as a result of any violation of this rule.

15. Landlord reserves the right to exclude or expel from the Building any person
who, in the judgement of Landlord, is intoxicated or under the influence of
liquor or drugs, or who shall in any manner do any act in violation of any of
the Rules and Regulations of the Building.

16. The requirements of Tenant will be attended to only upon application at the
Building management office. Employees of Landlord shall not perform any work or
do anything outside of their regular duties unless under special instructions
from the Landlord, and no employee will admit any person (Tenant or otherwise)
to any office without specific instruction from the Landlord.

17. Landlord shall have the right, exercisable without notice and without
liability to Tenant, to change the name and street address of the Building of
which the Premises are a part.

18. Without the prior written consent of Landlord, Tenant shall not use the name
of the Building to promote or advertise the business of Tenant except as
Tenant's address.

19. Tenant agrees to comply with all fire and security regulations that may
be issued from time to time by Landlord. Tenant shall also provide Landlord
with the name of a
<PAGE>

designated responsible employee to represent Tenant in all matters pertaining to
fire or security regulations.

20. Tenant shall not utilize electrical extension cords unless such cords are
equipped with a built in circuit breaker.

21. No curtains, draperies, blinds, shutters, shades, screens or other
coverings, hanging or decorations shall be attached to, hung or placed in, or
used in connection with any window of the Building without the prior written
consent of Landlord. Such window coverings as the Landlord does approve shall be
installed on the office side of Landlord's standard window covering and shall in
no way be visible from the exterior of the Building.

22. Except with the prior written consent of Landlord, Tenant shall not sell any
retail merchandise in or on the Premises, including but not limited to the sale
to the public of newspapers, magazines, periodicals, theater or travel tickets
or any other goods or merchandise. Tenant shall not carry on or permit any
employee or other person to carry on the business of stenography, typewriting,
printing or photocopying or any similar business in or from the Premises for the
service or accommodation of other occupants in the Building, nor shall the
Premises of Tenant be used for manufacturing of any kind, for lodging of any
kind, or for any business or activity other than that specified in the Tenant's
Lease Agreement.

23. Tenant shall store all its trash and garbage within its Premises. No
material shall be placed in the hallways or left for disposal by the Landlord.
All garbage and refuse disposal shall be made only through entryways and
elevators provided for such purposes and at such times as Landlord shall
designate.

24. Tenant shall not mark, paint, drive nails or drill into, cut, string wires
within, or in any way deface any part of the Building or the Premises, without
the prior written consent of Landlord and as Landlord may direct. Should
Landlord grant approval, Tenant agrees to assume full responsibility and
warrants that Tenant's contractor will strictly abide by Landlord's guidelines
for work contracted directly by Tenant. Upon removal of any and all decorations
or installations of floor covering by Tenant, any damage to walls or floor shall
be repaired by Tenant at Tenant's sole cost and expense. This paragraph shall
apply to all work performed in the Building, including without limitation
installation of telephone or computer equipment, electrical devices and
attachments and installations of any nature affecting floors, walls, woodwork,
trim, windows, ceilings, equipment or any other portion of the Building. Plans
and specifications for such work, prepared at Tenant's sole expense, shall be
submitted to Landlord and shall be subject to Landlord's prior written approval
in each instance before the commencement of work. All installations,
alterations, and additions shall be constructed by Tenant in a good and
workmanlike manner and only good grades of materials shall be used in connection
therewith. Tenant shall obtain any and all necessary or required permits for any
such work at its sole cost and expense.

25. Landlord reserves the right to rescind, alter or waive, by written notice to
Tenant, any rule or regulation prescribed for the Building when, in Landlord's
judgement, it is necessary, desirable or proper to take such action in the best
interest of the Building and its tenants. The waiver of a rule or regulation for
the benefit of a particular tenant or tenants shall not be construed as a waiver
of such rule or regulation in favor of any other tenant or tenants, nor shall
any such waiver prevent Landlord from thereafter enforcing the rules or
regulation in question against any or all tenants of the building.

26. These Rules and Regulations supplement and shall not be construed to modify
or amend the provisions of the Lease Agreement or other agreement between
Landlord and Tenant. In the event of any conflict between these Rules and
Regulations and the Lease Agreement and any agreement executed by Landlord and
Tenant, the Lease Agreement shall prevail.

27. Smoking of any kind is prohibited in all common areas within the Building
including but not limited to the lobby, hallways, passageways, exits, entrances,
elevators, stairways, restrooms and within thirty (30) feet of exterior Building
entryways. Cigar and pipe smoking is prohibited throughout the entire Building.

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