<PAGE>
                                                                 Exhibit 10.1.13

                                  OFFICE LEASE

                                     between

                         PARKSIDE SALT LAKE CORPORATION

                                    Landlord

                                       and

                        ADVANCED TELECOMMUNICATIONS, INC.

                                     Tenant

                             PARKSIDE TOWER BUILDING
                             215 South State Street
                              Salt Lake City, Utah
<PAGE>

                                TABLE OF CONTENTS

Section
-------
                                                                            Page
                                                                            ----
 1. Rentable Area of Premises .............................................. 6

 2. Term - Commencement Date and Expiration Date ........................... 6

 3. Rent and Other Payments ................................................ 6

 4. Security Deposit ....................................................... 8

 5. Personal Property Taxes ................................................ 9

 6. Use of Premises ........................................................ 9

 7. Condition of Premises: Repairs, Maintenance and Construction ........... 9

 8. Mechanics' Liens .......................................................10

 9. Building Services ......................................................10

10. Common Areas ...........................................................11

11. Landlords Right of Access ..............................................11

12. Indemnification and Waiver .............................................12

13. Insurance ..............................................................12

14. Damage or Destruction of Building or Premises ..........................14

15. Eminent Domain .........................................................14

16. Assigning - Mortgaging - Subletting - Change in Ownership ..............15

17. Subordination - Attornment .............................................16

18. Default ................................................................17

19. Remedies ...............................................................17

20. Rules and Regulations ..................................................18

21. Surrender of Premises ..................................................18

22. Holding Over ...........................................................19

23. Notices ................................................................19

24. Estoppel Certificates ..................................................19

25. Liability of Landlord ..................................................19

26. Landlord's Inability to Perform ........................................19


                                        2
<PAGE>

27. Attorneys Fees                                                          20

28. General Provisions                                                      20

Exhibit "A" Legal Description of Property                                   23

Exhibit "B" Drawings of Premises                                            24

Exhibit "C" Memorandum of Commencement Date Rentable Area                   25

Exhibit "D" Tenant Work Letter                                              26

Exhibit "E" Rules and Regulations                                           39

Exhibit "F" Tenant's Estoppel Certificate                                   42

Exhibit "G" Parking Provisions                                              43


                                        3
<PAGE>

                                  OFFICE LEASE

THIS OFFICE LEASE (this "Lease") is made this 28th day of December 1999,
between, PARKSIDE SALT LAKE CORPORATION, a Delaware corporation ("Landlord "),
and, ADVANCED TELECOMMUNICATIONS, INC., a Delaware corporation ("Tenant").

                                LEASE OF PREMISES

Landlord hereby leases to Tenant and Tenant hereby leases from Landlord, on the
terms and conditions hereinafter set forth, those premises (the Premises") set
forth in Item 2 of the Basic Lease Provisions and shown in the drawing attached
hereto as Exhibit "B", which Premises are a part of that office building (the
"Building") identified in Item 1 of the Basic Lease Provisions and situated on
that certain real property described in Exhibit "A" attached hereto (the
"Property").

                             BASIC LEASE PROVISIONS

<TABLE>
<S>                                 <C>
 1. Building Name and Address:      Parkside Tower Building
                                    215 South State Street
                                    Salt Lake City, Utah 84111

 2. Premises:                       The space on the 3rd, suite 380, as shown on
                                    Exhibit "B".
                                    -----------
    Rentable Area:                  Approximately 6,744 square feet.
    Usable Area:                    Approximately 5,796 square feet.

 3. Basic Annual Rent:              Basic Annual Rent       Monthly Installments
                                    -----------------       --------------------
    Year 1:                         $l14,648.00             $9,554.00
    Year 2:                         $116,334.00             $9,694.50
    Year 3:                         $119,706.00             $9,975.50
    Year 4:                         $123,078.00             $10,256.50
    Year 5:                         $124,764.00             $10,397.00
    Year 6:                         $128,136.00             $10,678.00
    Year 7:                         $129,822.00             $10,818.50
    Year 8:                         $131,508.00             $10,959.00
    Year 9:                         $133,194.00             $11,099.50
    Year 10:                        $134,880.00             $11,240.00

                                    Based on a beginning rate of $17.00 per year
                                    per square foot of Rentable Area.

 4. Tenant's Percentage:            3.6%
    Base Year:                      2000

 5. Scheduled Commencement Date:    On or about February 1, 2000.

 6. Expiration Date:                January 31, 2010

 7. Tenant Improvement Allowance:   $10.00/usable square foot or $57,960.00

 8. Security Deposit:               $20,000.00

 9. Guarantor(s):                   None

10. Tenant's Broker:                Tres Telecom Real Estate Services and CB
    Landlord's Broker:              Richard Ellis NAI Utah Commercial Real
                                    Estate - Collin Perkins
</TABLE>
<PAGE>

      AGENCY DISCLOSURE: At the signing of this Lease, the listing agent
      represents Landlord, and the leasing agent represents Tenant. Landlord and
      Tenant each confirm that prior to signing this Lease, this agency
      disclosure was acknowledged by both parties. (   ) Landlords Initials
      [ILLEGIBLE] Tenant's Initials

11. Use of premises:                      General office purposes.

12. Address for Payments and Notices:
      Landlord:                           Payments and Local Notices

                                          Cottonwood Management
                                          215 S. State, Suite 805
                                          Salt Lake City, UT 84111
                                          Attention: Lorrie Ostlind

    Tenant:                               Notices
                                          Advanced Telecommunications, Inc.
                                          730 2nd Avenue South, Suite 1200
                                          Minnesota, MN 55402

            IN WITNESS WHEREOF, the parties hereto have executed this Lease,
consisting of the foregoing provisions and Sections 1 through 28 of the
Additional Lease Provisions which follow, together with Exhibits "A" through "I"
incorporated herein by this reference, as of the date first above written.

LANDLORD:                                 TENANT:

PARKSIDE SALT LAKE CORPORATION            ADVANCED TELECOMMUNICATIONS, INC.

                                                                     PLEASE SIGN
                                                                       & DATE

By: /s/ [ILLEGIBLE]              RM       By: /s/ Satish C. Tiwari
    -------------------------------           ----------------------------------

Its: Asset Manager                        Its:       SATISH C. TIWARI
     ------------------------------                 V.P. ENGINEERING AND
                                                   NETWORK IMPLEMENTATION
                                             ADVANCED TELECOMMUNICATIONS, INC.
                                                 730 2ND AVE S. SUITE 1200
                                                   MINNEAPOLIS, MN 55402

Date: 1-11-2000                           Date: 12/30/1999
      -----------------------------             --------------------------------


                                       5
<PAGE>

                           ADDITIONAL LEASE PROVISIONS

SECTION 1. RENTABLE AREA OF PREMISES

            The Rentable Area of the Premises is provided in Item 2 of the Basic
Lease Provisions. For the purpose of this Lease, "Rentable Area" is calculated
pursuant to the Standard Method for Measuring Floor Area of Office Buildings,
ANSI 265.1-1980, commonly known as the "BOMA standard."

SECTION 2. TERM -- COMMENCEMENT DATE AND EXPIRATION DATE

            The term of this Lease shall commence on the date on which Tenant
first takes possession of the Premises. If Landlord is unable to deliver
possession of the Premises to Tenant on or before the Scheduled Commencement
Date, this Lease shall not be void or voidable, but rather, shall remain in full
force and effect except as otherwise provided in this Section 2. Landlord shall
not be subject to any liability to Tenant for any loss or damage resulting from
such non-delivery and Tenant's obligations hereunder shall not be affected
thereby. If Landlord is unable to deliver possession of the Premises to Tenant
within thirty (30) days after the Scheduled Commencement Date, Tenant shall have
the option to terminate this Lease, and Landlord shall not, by reason thereof,
be subject to any liability except that Landlord shall return to Tenant all
monies which Landlord has theretofore received from Tenant as prepaid rent or as
a security deposit, without interest; provided, however, Tenant's occupancy of
the Premises at any time shall conclusively be deemed a waiver of this
provision. The term of this Lease shall, unless this Lease is terminated sooner
as provided herein, end on the "Expiration Date" as provided in Item 6 of the
Basic Lease Provisions and shall not be extended by any such delay. The date
upon which the term of this Lease actually commences shall hereafter be referred
to as the "Commencement Date." The period from the Commencement Date through the
Expiration Date is the "Lease Term," unless it is sooner terminated as provided
herein. Within thirty (30) days after the Commencement Date, Landlord and Tenant
shall execute the memorandum attached hereto as Exhibit "C", but failure to do
so shall not affect Tenant's obligations under this Lease.

SECTION 3. RENT AND OTHER PAYMENTS

            3.1 Basic Annual Rent. Tenant shall pay to Landlord rent for the
Premises in an amount equal to the Basic Annual Rent set forth in Item 3 of the
Basic Lease Provisions for each year and a pro rata portion thereof for each
partial year during the Lease Term (the "Basic Annual Rent"). Basic Annual Rent
shall be paid in equal monthly installments in the amount set forth in Item 3 of
the Basic Lease Provisions, in advance and without prior notice, invoice or
demand, on the first day of each month commencing on the Commencement Date.
Basic Annual Rent payable for any period of less than one (1) month shall be
prorated based upon a thirty (30) day month.

            3.2 Additional Rent.

            3.2.1 Tenant's Share. In addition to Basic Annual Rent, Tenant shall
pay to Landlord, as additional rent ("Additional Rent"), the amount, if any, by
which Tenant's Share of Direct Expenses for each Expense Year exceeds Tenant's
Share of Direct Expenses for the Base Year. If the Lease Term falls partially
within an Expense Year, Tenant's share of Direct Expenses shall be equitably
prorated based upon a 360-day year consisting of twelve 30 day months, in
calculating the amount of Tenant's Additional Rent for such Expense Year.
Landlord may estimate Direct Expenses and Tenant's Additional Rent ("Estimated
Additional Rent") periodically, and after notice from Landlord of Estimated
Additional Rent for an Expense Year, Tenant shall pay Landlord, with each
installment of Basic Annual Rent, an amount equal to one-twelfth (1/12) of such
Estimated Additional Rent (or, if the Estimated Additional Rent is for a period
of less than twelve months, Tenant shall pay such Estimated Additional Rent on a
monthly basis ratably over the period to which such Estimated Additional Rent
relates).

            3.2.2 Definitions: As used in this Section 3.2, the following terms
have the meaning hereinafter set forth:

            (i) "Base Year" is the calendar year or other period described in
            Item 4 of the Basic Lease Provisions. The Base Year is an Expense
            Year.


                                       6
<PAGE>

            (ii) "Tenant's Share of Direct Expenses" for a given Expense Year is
            an amount equal to the Tenant's Percentage set forth in Item 4 of
            the Basic Lease Provisions multiplied by the amount of Direct
            Expenses for such Expense Year. If the Rentable Area of the Premises
            and/or the Rentable Area of the Building is changed, Tenant's
            Percentage shall be appropriately adjusted.

            (iii) "Expense Year" shall mean each twelve (12) consecutive month
            period commencing January 1st of each year.

            (iv) "Direct Expenses" shall mean "Operating Expenses" plus "Tax
            Expenses." If during any Expense Year the Building is on a monthly
            average less than ninety-five percent (95%) occupied, the Direct
            Expenses shall be increased to reflect the Direct Expenses which
            Landlord reasonably determines it would have so incurred had the
            Building been ninety-five percent (95%) occupied and the Additional
            Rent shall be based upon the Direct Expenses so adjusted.

            (v) "Operating Expenses" shall mean any and all costs and expenses
            paid or incurred by Landlord in connection with the operation,
            maintenance, management and repair of the Building and Property. By
            way of illustration but not limitation, Operating Expenses shall
            include the following: (A) the cost of supplying all utilities
            (unless Landlord elects to separately meter any utilities to the
            Premises, in which case Tenant shall pay directly the charges for
            those utilities and Operating Expenses shall not include similar
            utilities furnished to other tenants' premises), the cost of
            operating, maintaining, repairing and managing the utility systems,
            mechanical and heating systems, ventilation and air conditioning
            systems, sanitary and storm drainage systems, and escalator and
            elevator systems, the cost of environmental and energy surcharges
            imposed by any governmental entity, and the cost of supplies and
            equipment and maintenance and service contracts in connection
            therewith; (B) the cost of landscape maintenance, all supplies, and
            relamping; (C) the cost of parking area maintenance, including
            resurfacing, repainting and restriping, if applicable, (D) the cost
            of fire, extended coverage, all-risk, boiler, sprinkler, public
            liability, property damage, workmen's compensation, loss of rent,
            earthquake (only if available at commercially reasonable rates) and
            other or additional insurance that Landlord purchases for the
            Building and Property, including such endorsements thereto as
            Landlord may desire, all in such amounts as Landlord may reasonably
            determine; (E) wages, salaries and other labor costs, including
            payroll and employment taxes, and employee medical, welfare, pension
            and other fringe benefits for persons whose services are exclusively
            devoted to on-site management, security and maintenance of the
            Building and Property; (F) fees, charges and other costs, including
            (but not limited to) management fees, consulting fees, legal fees,
            accounting fees and security service fees, of all independent
            contractors engaged by Landlord (including any affiliates of
            Landlord) or reasonably incurred by Landlord in connection with the
            management, operation, maintenance and repair of the Building and
            Property; (G) the cost of licenses, permits and inspections and the
            cost of contesting the validity or applicability of any government
            enactments which may affect Operating Expenses; (H) the fair market
            rental value of the property manager's office in the Property; (I)
            depreciation of the cost of acquiring or the rental expense of
            personal property used in the maintenance, operation and repair of
            the Building and Property; and (J) the cost of any reasonable
            capital improvements made to the Building or Property as a
            labor-saving device or to effect other economies in the operation or
            maintenance of the Building or Property, or as required under any
            governmental law or regulation that was not applicable to the
            Building or Property at the time that permits for the construction
            thereof were obtained, or as periodically required to maintain the
            appearance of the Property and its first-class, competitive quality,
            such costs to be amortized over such reasonable period as Landlord
            shall determine, together with interest on the unamortized balance
            at a market rate. For purposes of this Lease, Operating Expenses
            shall not include "Tax Expenses"; principal or interest expense,
            except as provided in clause (J) above; leasing commissions and
            other costs related to leasing to, improvements for, disputes with
            or eviction of tenants in the Building; depreciation on the
            improvements contained in the Building or Property, except as
            provided in clause (I) above; or the cost of capital expenditures
            not included in clause (J) above. Additionally, for purposes of
            computing Tenant's Base Year, excluded from this calculation are all
            one-time expenses incurred by Landlord which are attributable to
            repair or replacement of deferred items noted during due


                                       7
<PAGE>

            diligence and acquisition of the Property. The computation of
            Operating Expenses shall be made in accordance with generally
            accepted accounting principles.

            (vi) "Tax Expenses" shall include real property taxes, current
            installments of any general or special assessments, license fees,
            commercial rental taxes, in lieu taxes, levies, charges, penalties
            or similar impositions, imposed by any authority having the direct
            power to tax against or attributable to any legal or equitable
            interest of Landlord in the Property, including tenant improvements
            and Changes (as hereafter defined) to the extent not paid directly
            by tenants, which are paid or incurred by Landlord, and which shall
            include, but not be limited to, the following:

                  (A) Any tax on Landlord's rent from the Property or as against
            Landlord's business of leasing any of the Property, but specifically
            excluding Landlord's federal, state or city income, franchise,
            inheritance or estate taxes;

                  (B) Any assessment, tax, fee, levy or charge imposed by
            governmental agencies for such services as fire protection, street,
            sidewalk and road maintenance, refuse removal and for other
            governmental services; and

                  (C) Any assessment, tax, fee, levy or charge, upon this
            transaction evidenced by this Lease or any document to which Tenant
            is a party, creating or transferring an interest or an estate in the
            Premises.

            3.2.3 Statement of Actual Direct Expenses. Landlord shall give to
Tenant on or before the end of each Expense Year falling in whole or in part
during the Lease Term, a statement (the "Statement") which shall state the
Direct Expenses incurred or accrued for such preceding Expense Year, and which
shall indicate the amount, if any, of Tenant's Additional Rent for such
preceding Expense Year. Upon receipt of the Statement for each Expense Year
falling in whole or in part during the Lease Term, if Tenant's Additional Rent
exceeds the amount of Estimated Additional Rent paid by Tenant for such Expense
Year, Tenant shall pay, with its next installment of Basic Annual Rent due, or,
if the Lease Term has ended, within thirty (30) days after the Statement is
rendered, the full amount of such deficiency. If payments of Estimated
Additional Rent made by Tenant for such Expense Year exceed the actual amount of
Tenant's Additional Rent, then Tenant shall receive a credit against future
payments of Additional Rent; provided, if any such credit has not been applied
as of the end of the Lease Term, Landlord shall pay Tenant an amount equal to
such unapplied credit on or before the last to occur of: (i) the thirtieth
(30th) day following the last day of the Lease Term; or (ii) the thirtieth
(30th) day following the delivery to Tenant of the Statement setting forth such
credit. The failure of Landlord to timely furnish the Statement for any Expense
Year shall not prejudice Landlord from enforcing its rights under this Section
3.

            3.3 Payment of Rent. All amounts payable by Tenant to Landlord under
this Lease shall be deemed to be rent and, except as expressly provided in this
Lease, shall be payable to Landlord without abatement, deduction or offset, at
Landlord's address as provided in Item 13 of the Basic Lease Provisions or to
such other persons or at such other places as Landlord designates in writing. If
Tenant's obligation to pay any rent accrues prior to the expiration or earlier
termination of this Lease, then such obligation shall survive such expiration or
termination, even if the amount is not then due or calculated.

SECTION 4. SECURITY DEPOSIT

            Tenant has deposited with Landlord the amount indicated in Item 8 of
the Basic Lease Provisions as security for the full and faithful performance of
each and every provision of this Lease to be performed by Tenant. If Tenant
defaults with respect to any provision of this Lease, Landlord may (but shall
not be required to) use, apply or retain all or any part of this security
deposit for the payment of any rent or any other sum in default, or for the
payment of any other amount which Landlord may spend or become obligated to
spend by reason of Tenant's default or to compensate Landlord for any other loss
or damage which Landlord may suffer by reason of Tenant's default. If any
portion of said deposit is so used or applied, Tenant shall, within five (5)
days after written demand therefor, deposit cash with Landlord in an amount
sufficient to restore the security deposit to its original amount. Prior to the
time when Tenant is entitled to any return of the security deposit, Landlord may
intermingle such deposit with its own funds and use such sum for such purposes
as Landlord may determine. Tenant shall not be entitled to any interest on the
security deposit.


                                       8
<PAGE>

SECTION 5. PERSONAL PROPERTY TAXES

            With respect to Tenant's trade fixtures, furnishings, equipment and
all other personal property located in the Premises, and any improvements made
to the Premises in excess of Landlord's building standard tenant improvements,
(i) Tenant shall be liable for and pay at least ten (10) days prior to
delinquency all taxes assessed against or levied thereon ("Tenant's Taxes") and
(ii) when possible, Tenant shall cause Tenant's Taxes to be assessed and billed
separately from the taxes on the Property of Landlord; but if Tenant's Taxes
shall be assessed and taxed with the Property, Tenant shall pay them to Landlord
within ten (10) days after Landlord's delivery to Tenant of a statement in
writing setting forth the amount of Tenant's Taxes.

SECTION 6. USE OF PREMISES

            6.1 Limitation of Use. Tenant shall use and occupy the Premises
solely for the purpose stated in Item 11 of the Basic Lease Provisions and shall
not use or occupy the Premises or permit the same to be used or occupied for any
other purpose without the prior written consent of Landlord. Tenant agrees that
it will not do or permit anything to be done in or about the Premises which will
in any way obstruct or interfere with or infringe upon the rights of other
tenants or occupants of the Building or Property, or to injure or annoy them, or
use or allow the Premises to be used for any improper, immoral, unlawful or
objectionable purpose, nor shall Tenant cause, maintain or permit any nuisance
in, on or about the Premises.

            6.2 Compliance With Governmental and Insurance Regulations. Tenant
shall not do or permit to be done anything that will invalidate or increase the
cost of any fire, extended coverage or other insurance policy covering the
Building, and Tenant shall promptly upon demand reimburse Landlord for any
additional premium charges for such policy or policies caused by reason of
Tenant's failure to comply with the provisions of this Section 6.2. Tenant shall
not bring or permit to remain on the Premises any Hazardous Substances, except
usual office supply products used and stored in usual quantities and manner. As
used in the preceding sentence, the term "Hazardous Substances" means any
hazardous or toxic substances, materials or wastes, including, but not limited
to, those substances, materials, and wastes listed in the United States
Department of Transportation Hazardous Materials Table (49 CFR ss. 172.101) or
by the Environmental Protection Agency as hazardous substances (40 CFR Part 302)
and amendments thereto, or such substances, materials and wastes which are or
become regulated under any applicable local, state or federal law including,
without limitation, any material, waste or substance which is (i) petroleum,
(ii) asbestos, (iii) polychlorinated biphenyls, (iv) defined as a "hazardous
waste," under Section 19-6-102 of the Utah Code Annotated, Solid and Hazardous
Waste Act, or any rule promulgated thereunder, (v) designated as a "hazardous
substance" pursuant to Section 311 of the Clean Water Act, 33 U.S.C. ss. 1251,
et seq. (33 U.S.C. ss. 1321) or listed pursuant to Section 307 of the Clean
Water Act (33 U.S.C. ss. 1317), (vi) defined as a "hazardous waste" pursuant to
Section 1004 of the Resource Conservation and Recovery Act, 42 U.S.C. ss. 6901,
et seq. (42 U.S.C. ss. 6903) or (vii) defined as a "hazardous substance"
pursuant to Section 101 of the Comprehensive Environmental Response,
Compensation, and Liability Act, (42 U.S.C. ss. 9601).

SECTION 7. CONDITION OF PREMISES: REPAIRS, MAINTENANCE AND CONSTRUCTION

            7.1 Condition of Premises. Tenant acknowledges that neither Landlord
nor any agent of Landlord has made any representation or warranty with respect
to the Building or the Premises or with respect to the suitability of either for
the conduct of Tenant's business. Tenant hereby agrees to take the Premises in
their "as is" condition, subject to the provisions of Section 7.2.2 and Exhibit
"D" attached hereto. The taking of possession of the Premises by Tenant shall
conclusively establish that the Premises and the Building were at such time in
good sanitary order, condition and repair.

            7.2 Maintenance and Repair.

            7.2.1 Tenant Repairs and Maintenance. Tenant shall at its sole cost
and expense keep and maintain in good and tenantable condition and repair, the
Premises and every part thereof, including, without limitation, the floor
coverings, interior walls, ceiling, doors, drapes and other window treatments,
plumbing, fixtures and equipment therein. Tenant shall not commit or suffer to
be committed any waste in or upon the Premises, nor effect any Changes, nor do
anything in or on the Premises that, in Landlord's sole opinion, detracts


                                       9
<PAGE>

from the quality or appearance of the Building. All damage or injury to the
Premises, caused by the act or negligence of Tenant, its employees, agents,
invitees, permittees, licensees or contractors shall be promptly repaired by
Tenant, at its sole cost and expense, to the satisfaction of Landlord, and
subject to such requirements respecting construction that Landlord shall
reasonably impose. Landlord may but shall not be obligated to make any repairs
that are not promptly made by Tenant and to charge Tenant for the cost thereof.
Tenant hereby expressly and irrevocably waives the benefit or applicability of
any statute or law now or hereafter in effect that would otherwise afford Tenant
the right to make repairs at Landlord's expense or to terminate this Lease
because of Landlord's failure to comply with the provisions of Section 7.2.2.

            7.2.2 Landlord Repairs and Maintenance. Landlord shall maintain and
repair the structural, mechanical and utility elements and Common Areas of the
Building and Property. Any restriction on or interference with Tenant's access
to the Premises shall be limited to the minimum amount necessary to accomplish
the maintenance or repair work. Rent under this Lease shall not be abated as a
result of any such activities unless Tenant's access to the Premises is
prevented for more than 48 hours in which case, except as provided in the next
sentence, the rent shall abate for the balance of such obstruction. If the need
for repairs was caused by any act or negligence of Tenant or its employees,
agents, invitees, permittees, licensees or contractors, then such repairs shall
be performed at Tenant's expense and no abatement of rent shall occur.

            7.3 Construction of Improvements to the Premises. Except for
alterations, additions, modifications or improvements (collectively, "Changes")
expressly required or permitted by this Lease, Tenant shall not make any Changes
to the Premises or any part thereof without Landlord's prior written consent,
which consent shall not be unreasonably withheld or delayed. To the extent
permitted or consented to hereunder, any construction undertaken in or to the
Premises shall be performed in accordance with this Section and any reasonable
requirements then imposed by Landlord. All Changes made in or to the Premises
shall become the property of Landlord and a part of the realty. All initial
tenant improvements to the Premises, and all later Changes to the Premises that
are non structural that cost in excess of twenty thousand dollars ($20,000)
shall, at Landlord's option, be performed by Landlord or its contractor. Any
later Changes to the Premises costing less than twenty thousand dollars
($20,000), or later Changes that cost $20,000 or more which Landlord elects not
to construct may be constructed by Tenant, subject to reasonable construction
and other requirements then imposed by Landlord, including the right to
reasonably approve all plans and specifications and charge Tenant a supervision
fee equal to five percent (5%) of the cost of such work. Landlord shall pay for
the cost of initial improvements to the Premises in accordance with the
provision of Exhibit "D" attached hereto up to the amount of the "Tenant
Improvement Allowance" specified in Item 7 of the Basic Lease Provisions, if
any, and the balance shall be paid by as provided for in Exhibit "D". Unless
otherwise expressly provided in this Lease, Tenant shall pay all costs of any
later Changes to the Premises.

SECTION 8. MECHANICS' LIENS

            Tenant hereby agrees to keep the Property free from any liens
arising out of any work performed, materials furnished or obligations incurred
by or on behalf of Tenant and to promptly notify Landlord if it learns of any
such liens.

SECTION 9. BUILDING SERVICES

            9.1 Provision of Services. So long as Tenant is not in default
hereunder, Landlord agrees, subject to the terms and conditions hereinafter set
forth, to furnish or provide for the furnishing to the Premises (i) air
conditioning, heat, lighting, and elevator service only during the hours of 7:30
a.m. to 6:00 p.m. Monday through Friday, except legal holidays, and 8:00 a.m. to
1:00 p.m. Saturdays, in such quantity and of such quality as Landlord determines
in its sole judgment is reasonably necessary for Tenant's comfortable use and
enjoyment of the Premises for general office purposes and, at all other times,
to provide air conditioning, heating and lighting at Landlord's prevailing rate,
and one elevator; (ii) on the same floor as the Premises, water for lavatory and
drinking purposes at all times when the Premises are occupied; (iii) routine
janitorial services five (5) days per week (except for legal holidays); and (iv)
maintenance of the Common Areas. No gas shall be provided to or permitted in the
Premises. Electricity service and costs therefor, except electricity used for
before or after hours lighting or electricity that is separately metered, are
the obligations and expense of Landlord, as Operating Expenses, provided
Landlord is entitled to reimbursement therefor to the extent such costs are
included in Additional Rent. Tenant shall arrange for and shall pay the entire
cost and expense of all materials and services


                                       10
<PAGE>

relating to or used on the Premises not expressly required to be provided and
paid for by Landlord pursuant to this Lease.

            9.2 Interruption of Services. Landlord shall under no circumstances
be liable in damages or otherwise for any failure or interruption of, or
reduction in any utility service or Building service being furnished to the
Premises by Landlord or otherwise and no such failure or interruption shall
under any circumstances entitle Tenant to withhold, reduce or abate any rent or
terminate this Lease, regardless of whether caused by riot, strike, lockout,
labor disputes, breakage, breakdowns, accidents, repairs, governmental
regulation or moratorium, any act or omission of Tenant or its employees,
agents, invitees, licensees, customers or visitors or any other cause.

            9.3 Additional Building Service Demands. Tenant shall not install
any computers, copiers or other electrical office equipment in the Premises
without Landlord's prior written approval. Should any equipment installed by
Tenant produce any significant amount of heat or cause any significant
additional usage or draw on the electrical or other utility system, Landlord
shall not be responsible for the adequacy of any air conditioning, electric
current or other utilities affected thereby, and to the extent Tenant uses or
requests additional utilities or Building services as a result thereof, Tenant
shall pay to Landlord an amount reasonably estimated by Landlord to be the
additional costs incurred thereby. If and where heat generating machines or
devices are used in the Premises which affect the temperature otherwise
maintained by the air conditioning system, Landlord reserves the right to
install additional or supplementary air conditioning units for the Premises or
other affected areas of the Building, and the entire cost of installing,
operating, maintaining and repairing the same shall be paid by Tenant to
Landlord promptly after demand by Landlord.

SECTION 10. COMMON AREAS

            The term "Common Areas" as used herein shall mean all areas and
facilities outside the Premises or premises leased to other tenants of the
Property and within the exterior boundaries of the Property which are provided
and designated from time to time by Landlord for the general use and convenience
of Tenant and other tenants of the Property and their respective employees,
invitees or other visitors. Common Areas include, without limitation, walkways,
sidewalks, service quarters, hallways, restrooms (if not part of the premises),
stairways, elevators and walls, except to the extent situated entirely within
the Premises or premises leased to other tenants of the property. Tenant, its
employees and invitees shall have the nonexclusive right to use the Common Areas
along with others entitled to use same, subject to Landlord's rights and duties
as hereinafter set forth. Landlord shall have the right to temporarily close or
obstruct the Common Areas or any part thereof for maintenance, alteration,
addition or improvement purposes, or to protect Landlord's legal rights, and to
change the size, use, shape or nature of any such Common Areas and remove
portions of the Common Areas from Tenant's use, provided such change does not
deprive Tenant of the substantial benefit and enjoyment of the Common Areas or
its Premises.

SECTION 11. LANDLORD'S RIGHT OF ACCESS

            Landlord reserves for itself at any and all times the right to enter
the Premises and to take materials and equipment therein, as necessary, for
purposes of (i) providing janitorial services and any other service to be
provided by Landlord to Tenant hereunder; (ii) examining or inspecting the
Premises; (iii) serving or posting notices of non- responsibility; (iv) showing
the same to prospective tenants or mortgagees of the Premises or purchasers of
the Building; (v) emergency entry, by force if necessary; (vi) entry by security
personnel during non-business hours to make security checks; or (vii) making
such Changes or repairs to the Premises or to any other portion of the Building
as Landlord may deem necessary or desirable, including the installation of
sprinklers in the Premises and Building, all without being deemed guilty of an
eviction of Tenant and without abatement of rent. Landlord shall at all times
have and retain a key with which to unlock all of the doors in, upon and about
the Premises, excluding Tenant's vaults and safes. Landlord shall have the right
to place, maintain, and repair all utility equipment of any kind in, upon, and
under the premises as may be necessary for the servicing of the premises or
other portions of the Building.

SECTION 12. INDEMNIFICATION

            12.1 Indemnification. To the extent not prohibited by law, Landlord,
its partners, trustees ancillary trustees, and their respective officers,
directors, shareholders, members, beneficiaries, agents, servants, employees,
and independent contractors (collectively, "Landlord Persons") shall not be
liable for any damage,


                                       11
<PAGE>

claims, or loss either to person or property, or resulting from the loss of use
thereof, which damage is sustained by Tenant or by other persons claiming
through Tenant; provided, however, nothing herein is intended to limit the
liability of each of the Landlord Persons for damage arising solely from his,
her or its own gross negligence or intentional misconduct, which gross
negligence or intentional misconduct of Landlord Persons other than Landlord
itself, shall not be imputed to Landlord. Tenant agrees to indemnify, defend,
and hold Landlord harmless from all claims, costs, expenses, losses, damages,
and liabilities, including attorney's fees, except those caused solely by
Landlord's negligence, gross negligence or intentional misconduct, arising or
resulting from (a) any accident, injury, death, loss, or damage to any person or
to any property, including without limitation, the person and property of the
Tenant and its partners, trustees, officers, directors, shareholders, members,
beneficiaries, licensees, invitees, or any subtenants or subtenants' agents,
employees, contractors, or invitees, servants, guests, or independent
contractors ("Tenant Persons"), and all other persons at any time in the
building or the Premises or the Common Areas, (b) the occupancy or use of the
Premises by the Tenant, or (c) any act or omission or negligence of Tenant
Persons. The indemnification obligations of Tenant under this Lease shall
survive the expiration or earlier termination of this Lease.

            12.2 Tenants Compliance with Landlord's Fire and Casualty Insurance.
Tenant shall, at Tenant's expense, comply as to the Premises with all insurance
company requirements pertaining to the use of the Premises. If Tenant's conduct
or use of the Premises causes any increase in the premium for such insurance
policies, then Tenant shall pay Landlord for nay such increase. Tenant, at
Tenant's expense, shall comply with all rules, orders, regulations or
requirements of the American Insurance Association (formerly the National Board
of Fire Underwriters) and with any similar body.

SECTION 13. INSURANCE

            13.1 Tenant's Insurance. Tenant shall maintain the following
coverages in the following amounts.

                  13.1.1 Commercial General Liability Insurance covering the
insured against claims of bodily injury, personal injury, and property damage
arising out of Tenant's operations, assumed liabilities, or use of the Premises,
including a Broad Form Commercial General Liability endorsement covering the
insuring provisions of this Lease and the performance by Tenant of the indemnity
agreements set forth in Section 12.1 of this Lease, for limits of liability not
less than:

            Property Injury and                  $2,000,000 each occurrence
            Property Damage Liability            $2,000,000 annual aggregate

            Personal Injury Liability            $2,000,000 each occurrence
                                                 $2,000,000 annual aggregate

                  13.1.2 Physical Damage Insurance covering (i) all office
furniture, trade fixtures, office equipment, merchandise, and all other items of
Tenant's property on the Premises installed by, for, or at the expense of
Tenant, (ii) the Tenant Improvements, including any Tenant Improvements which
Landlord permits to be installed above the ceiling of the Premises or below the
floor of the Premises, and (iii) all other improvements, alterations, and
additions to the Premises, including any improvements, alterations, or additions
installed at Tenant's request above the ceiling of the Premises or below the
floor of the Premises. Such insurance shall be written on an "all risks" of
physical loss or damages basis, for the full replacement cost value new without
deduction for deprecation of the covered items and in amounts that meet any
co-insurance clauses of the policies of insurance and shall include a vandalism
and malicious mischief endorsement, and sprinkler leakage coverage.

                  13.1.3 Loss-of-income and extra-expense insurance in such
amounts as will reimburse Tenant for direct or indirect loss of earnings
attributable to all perils commonly insured against prudent tenants or
attributable to prevention of access to the Premises or to the Building as a
result of such perils.

                  13.1.4 The minimum limits of policies of insurance required of
Tenant under this Lease shall in no event limit the liability of Tenant under
this Lease. Such insurance shall (i) name Landlord, and any other party it so
specifies, as an additional insured; (ii) specifically cover the liability
assumed by Tenant under this Lease, including, but not limited to, Tenant's
obligations under Section 12.1 of this Lease; (iii) be


                                       12
<PAGE>

issued by an insurance company having a rating of not less than A-X in Best's
Insurance Guide or which is otherwise acceptable to Landlord and licensed to do
business in the state in which the Building is located; (iv) be primary
insurance as to all claims thereunder and provide that any insurance carried by
Landlord is excess and is non-contributing with any insurance requirement of
Tenant; (v) provide that said insurance shall not be canceled, expire, or
coverage changed unless thirty (30) days' prior written notice shall have been
given to Landlord and any mortgagee or ground or underlying lessor of Landlord;
and (vi) contain a cross-liability endorsement or severability of interest
clause acceptable to Landlord. Tenant shall deliver said policy or policies or
certificates thereof to Landlord on or before the Commencement Date and at least
thirty (30) days before the expirations dates thereof. In the event Tenant shall
fail to procure such insurance, or to deliver such policies or certificate,
Landlord may, at its option, procure such policies for the account of Tenant,
and the cost thereof shall be paid to Landlord as additional Rent within five
(5) days after delivery to Tenant of bills thereof.

            13.2 Subrogation. Landlord and Tenant agree to request that their
respective insurance companies issuing property damage insurance waive any
rights of subrogation that such companies may have against Landlord or Tenant,
as the case may be, so long as the insurance carried by Landlord or Tenant,
respectively, is not invalidated thereby. As long as such waivers of subrogation
are contained in their respective insurance policies, and subject to Section 14,
Landlord and Tenant hereby waive any right that either may have against the
other on account of any loss or damage to their respective property to the
extent such loss or damage is actually insured under policies of insurance for
fire, all risk coverage, theft, public liability, or other similar insurance.

            13.3 Additional Insurance Obligations. Tenant shall carry and
maintain during the entire Lease Term, at Tenant's sole cost and expense the
insurance required to be carried by Tenant pursuant to this Section 13, and such
other reasonable types of insurance coverage and in such reasonable amounts
covering the Premises and Tenant's operations therein, as may be reasonably
requested by Landlord. Tenant shall not do or permit to be done anything which
shall cause the cancellation of, invalidate, increase the rate of, or otherwise
adversely affect, the insurance policies referred to in this Section 13.

            13.4 No Gap In Coverage. All insurance provided by Tenant under this
Lease shall be coordinated with any preceding, concurrent or subsequent,
occurrence or claims made in insurance, in such a manner as to avoid any gap in
coverage against claims arising out of occurrences, conduct or events which take
place during the period beginning on the Lease Date and ending on termination of
this Lease.

            13.5 No Landlord Representation. Landlord makes no representation
that the insurance coverage required of Tenant provides adequate coverage for
Tenant's needs or for its obligations under this Lease. Nothing in this Lease is
intended to make Tenant an insured party in any manner under any insurance
policy carried by Landlord.

            13.6 No Waiver of Insurance Requirements. Landlord shall not be
deemed to have waived or reduced any of the insurance coverage requirements for
Tenant except by an express written agreement to that effect. The receipt by
Landlord or its contractors or agents of insurance policies, certificates,
letters, or other correspondence, documents or information which do not conform
to the insurance requirements of this Lease, or the failure of Landlord to
receive policies, certificates, or other documentation requires by this Section
13, shall not be deemed to be Landlord's consent to a waiver or reduction of any
such requirements, despite any failure by landlord to object to same at the time
of receipt (or lack of receipt), or thereafter. Any reduction, modification, or
waiver of any of Tenant's insurance requirements under this Lease may be made
only by written document signed by Landlord and Tenant which expressly amends
the pertinent described portions of this Lease.

SECTION 14. DAMAGE OR DESTRUCTION OF BUILDING OR PREMISES

            14.1 Partial Damage. Except as provided in Section 7.2, if the
Premises or the Building is damaged by fire or other insured casualty and the
insurance proceeds have been made available therefor by the holder or holders
of any mortgages or deeds of trust covering the Property, the damage shall be
repaired by Landlord; provided, if (a) such repairs cannot, in Landlord's sole
opinion, be made within ninety (90) days after the occurrence of such damage
without the payment of overtime or other premiums; (b) such repairs cannot be
made at a cost equal to or less than the amount of insurance proceeds available
therefor; (c) the Premises by reason


                                       13
<PAGE>

of such damage are rendered wholly untenantable; (d) the Premises are damaged in
whole or in part during the last six (6) months of the Lease Term; or (e) the
Premises or the Building (whether the Premises are damaged or not) should be
damaged to the extent of fifty percent (50%) or more of the then-monetary value
thereof, then Landlord shall not be required to make such repairs but may, at
its discretion, elect to do so. Landlord's election to make such repairs must be
evidenced by written notice to Tenant within ninety (90) days of Landlord's
learning of the occurrence of the damage. Any reconstruction or repair of the
Premises Landlord is required or elects to make in accordance with the
provisions of this Section 14.1 shall be substantially to the condition that
existed immediately prior to the damage or destruction. If Landlord is not
required to make such repairs and does not elect to make them then either party
may, by written notice to the other, cancel this Lease as of the date of the
occurrence of such damage, provided, Tenant may not elect to terminate this
Lease if the damages to the Premises were due to the act, omission, fault or
neglect of Tenant or its employees, agents or visitors. If any policy of
insurance required to be obtained by Tenant under this Lease covers any damage
or loss which Landlord is required or elects to repair under this Section 14.1,
Tenant shall take such action as may be necessary to collect the proceeds of
such insurance relating to such damage or loss and shall pay such proceeds to
Landlord.

            14.2 Tenant Reconstruction Obligation. Tenant shall be required to
repair or replace at its sole cost and expense Tenant's trade fixtures,
furniture, equipment and other personal property in the Premises.

            14.3 Rent Abatement. In the event of any repair, reconstruction and
restoration as provided in Sections 14.1, Tenant's rent shall be equitably
abated proportionately with the degree to which Tenant's use of the Premises is
impaired commencing from the date of destruction and continuing during the
period of such repair, reconstruction or restoration, provided, however, that
there shall be no rent abatement whatsoever if either (i) the damage is due to
the act, omission, fault or neglect of Tenant or its employees, agents or
visitors or (ii) if the use and enjoyment of the Premises is not affected for
more than two (2) business days of operation.

            14.4 Notice of Casualty. Tenant shall give prompt notice to Landlord
of any casualty or accident of which Tenant is aware occurring in the Premises
or in the Building and any defects therein or damages thereto or in any fixtures
or equipment.

SECTION 15. EMINENT DOMAIN

            15.1 Partial Taking. If there is a taking of or damage to less than
the entire Premises, then with respect to that portion of the Premises not taken
or damaged, this Lease shall continue in effect and the Basic Annual Rent and
Tenant's Share shall be reduced or adjusted proportionately. Landlord shall, as
promptly as possible, restore, repair and replace that portion of the Premises,
Building or Common Areas not so taken or damaged to a complete architectural
unit or units for the use and occupancy of Tenant and other tenants and, as
nearly as possible, to the condition existing prior to the taking or damaging.
Landlord shall not be required to expend for such work an amount in excess of
the amount received by Landlord as damages for the part of the Property so taken
less amounts required to be paid by Landlord to mortgage lenders.
Notwithstanding the foregoing, Landlord or Tenant may elect, within thirty (30)
days after the taking or damaging, to terminate this Lease if (i) twenty percent
(20%) or more of the Premises or Building are taken or damaged, or (ii) so much
of the parking areas of the Property are taken or damaged that Tenant cannot be
assured the use of the number of parking spaces required by municipal code,
considering the similar usage of other tenants at the Property. In order to
terminate this Lease, Landlord shall deliver written notice to Tenant, which
notice shall specify a termination date at least thirty (30) days and not more
than ninety (90) days from the date thereof. In such event, Landlord shall not
be required to repair, restore or reconstruct the Premises.

            15.2 Allocation of Award. The entire award or compensation,
including interest, whether for a total or partial taking or damaging or for a
diminution in the value of Tenant's leasehold or Landlord's fee or other
interest, shall belong to and be the property of Landlord, and Tenant hereby
assigns to Landlord all of Tenant's interest in any award. Tenant shall have the
right to prove in the proceedings related to the taking or damaging loss of, and
to receive any separate award which may be made for damage to or condemnation
of, Tenant's equipment, trade fixtures, furniture and furnishings, and for
relocation costs and goodwill.

            15.3 Definitions. As used in this Section 15, (i) the term "taking
or damaging" shall include inverse condemnation, or any transfer made in
avoidance of the power of eminent domain; and (ii) the "award"


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<PAGE>

shall include all monies awarded for a taking or damaging occurring before or
after the commencement of litigation proceedings.

SECTION 16. ASSIGNING - MORTGAGING - SUBLETTING - CHANGE IN OWNERSHIP

            16.1 No Transfer or Sharing Without Consent. Tenant shall not
assign, sublet, enter into a license or concession agreement for, hypothecate or
otherwise divest itself of this Lease or any of its rights hereunder
(collectively, a "transfer of rights") or permit any third party or parties
other than Tenant, its authorized agents, employees, invitees and visitors to
occupy the Premises or any portion thereof (collectively, a "sharing of the
Premises") without Landlord's prior written consent, which consent may be
withheld in Landlord's sole discretion. Unless Landlord expressly agrees
otherwise, Tenant shall not be relieved of any of its duties or obligations
under this Lease as a result of any transfer of rights or sharing of the
Premises, regardless whether consented to by Landlord. Such prohibition against
the transfer of rights shall include any transfer of rights by operation of law.
Any attempted transfer of rights or sharing of the Premises without Landlord's
advance written consent shall constitute a default hereunder and shall be void
ab initio so as not to confer any rights upon any third person. Consent to any
transfer of rights shall not operate as a waiver of the necessity for consent to
any subsequent transfer of rights, and the terms of such consent shall be
binding upon any person holding by, under, or through Tenant. The provisions of
Section 16.2 hereof constitute the sole means by which such consent may be
requested. If a transfer of rights occurs or if there is a sharing of the
Premises, Landlord may collect rent and other charges from such assignee or
other party, and apply the amount collected to the rent and other charges
reserved hereunder, but such collection shall not constitute consent or waiver
of the necessity of consent to such transfer or sharing of the Premises, nor
shall such collection constitute the recognition of such assignee, sublessee, or
other party as the Tenant hereunder or a release of tenant from the further
performance of all of the covenants and obligations of Tenant herein contained.

            Any transfer of this Lease or of Tenant's rights hereunder by
merger, consolidation, transfer of assets or liquidation shall constitute a
transfer of rights. In the event that Tenant is a corporation, an unincorporated
association, or a partnership, the transfer, assignment or hypothecation of any
stock or interest in such corporation, association or partnership in the
aggregate in excess of 49% of the total outstanding stock or interest shall be
deemed a transfer of rights.

            Related Entity: Notwithstanding the provisions of Section 16.1
above, Tenant may assign this Lease or sublet the Premises, or any portion
thereof, without Landlord's consent to any entity resulting from a merger or
consolidation of Tenant with any other entity, (ii) any entity purchasing all or
substantially all of the stock or assets of Tenant, (iii) any entity succeeding
to all or substantially all of the business and all or substantially all of the
assets of Tenant, or (iv) any entity which controls, is controlled by or is
under common control with Tenant, provided that (a) the assignee or sublessee
assumes, in full, the obligations of Tenant under this Lease, (b) Tenant remains
fully liable under this Lease, (c) the use of the Premises under Section 6
remains unchanged, and (d) Landlord shall have received an executed copy of the
assignment or sublease on or before its effective date (e) the net worth of the
entity is equal or greater than Tenant as of the effective date. No change of
stock ownership or control or partnership change, assignment, transfer or
hypothecation of any partnership or other ownership interest in Tenant shall
constitute an assignment hereunder.

            16.2 Procedure for Requesting Consent. If Tenant desires at any time
to effect a transfer of rights or sharing of the Premises it must first notify
Landlord in writing of its desire to do so and shall submit in writing to
Landlord (i) the name of the third party concerned; (ii) the nature of the third
party's business proposed to be carried on in the Premises; (iii) the terms and
provisions of the proposed transfer of rights or sharing of the Premises; and
(iv) such financial and business information as Landlord may reasonably request
concerning the third party. Submission to Landlord by Tenant of an executed
sublease or other document purporting to make a transfer of rights or sharing of
the Premises subject to Landlord's approval shall constitute a request for
Landlord's consent under this Section 16.2.

            16.3 Conditions of Authorization. As conditions precedent to
Landlord's consent to Tenant's transfer of rights or sharing of the Premises,
Landlord may require, without limitation, any or all of the following:


                                       15
<PAGE>

            (a)   Tenant shall reimburse Landlord for Landlord's reasonable
                  attorneys' fees incurred in connection with the review,
                  processing and documentation of such request;

            (b)   If Tenant's transfer of rights or sharing of the Premises
                  provides for the receipt by, on behalf or on account of Tenant
                  of any consideration of any kind whatsoever (including, but
                  not by way of limitation, a premium rental for a sublease or
                  lump sum payment for an assignment) in excess of the rental
                  and other charges due Landlord under this Lease, Tenant shall
                  pay one hundred percent (100%) of said excess to Landlord when
                  such consideration is received by Tenant;

            (c)   In the event of a sublease or sharing of the Premises, the
                  third party shall agree in writing that in the event Landlord
                  gives such third party notice that Tenant is in default under
                  this Lease, such third party shall thereafter make all
                  payments otherwise due Tenant directly to Landlord, which
                  payments will be received by Landlord without any liability of
                  Landlord except to credit such payment against those due under
                  the Lease, and any such third party shall agree to attorn to
                  Landlord or its successors and assigns should this Lease be
                  terminated for any reason; provided however that in no event
                  shall Landlord or its successors or assigns be obligated to
                  accept such attornment;

            (d)   In the case of an assignment of this Lease, the assignee shall
                  agree in writing to assume, be bound by and perform all of the
                  terms, covenants and conditions of this Lease;

            (e)   Tenant shall not then be in default hereunder in any respect;
                  and

            (f)   Tenant shall deliver to Landlord one executed copy of any and
                  all written instruments evidencing or relating to Tenant's
                  transfer of rights or sharing of the Premises.

            16.4 Right of Termination. Notwithstanding any other provision
hereof, in lieu of giving such consent, Landlord may at its election, elect to
(i) construe such proposed transfer of rights or sharing of the Premises as an
offer to Landlord on the same terms and conditions as with the third party,
which offer may be accepted at any time within thirty (30) days after receipt
thereof, and if so accepted, such transfer of rights to or sharing of the
Premises with Landlord shall automatically be deemed consummated on all the
terms and provisions set forth in such proposed transfer (except that Landlord
may further assign or otherwise transfer such interest without Tenant's review
or consent) or (ii) terminate this Lease (or in the case of a proposed
subletting or assignment of a portion of the Premises, elect to terminate this
Lease as respects that portion) upon thirty (30) days' prior notice and release
Tenant from any liability under this Lease (as to that portion of the Premises
involved) accruing after the effective date of such termination.

SECTION 17. SUBORDINATION - ATTORNMENT

            17.1 Subordination. At Landlord's request, Tenant agrees to
subordinate this Lease to the lien of any mortgages or deeds of trust in any
amount hereafter placed on or against the Property and if Landlord elects to
make any such lien subordinate to this Lease, Tenant hereby consents and agrees
to such election. Tenant agrees that at the request of Landlord at any time and
from time to time Tenant shall execute and deliver to Landlord an instrument, in
form reasonably acceptable to Landlord, evidencing such subordination. Tenant
shall not subordinate this Lease to any such lien except at the request or with
the written consent of Landlord. Tenant, at the written request of any person
that acquires Landlord's interest in this Lease by sale, assignment, transfer,
foreclosure, termination of a ground lease or otherwise, shall attorn to such
person and its successors and assigns.

            17.2 Quiet Enjoyment. Upon Tenant paying the Basic Annual Rent and
all Additional Rent and performing all of Tenant's obligations under this Lease,
Tenant may peacefully and quietly enjoy the Premises during the Lease Term as
against all persons or entities lawfully claiming by or through Landlord,
subject, however, to the provisions of this Lease and to any mortgages
encumbering the Property.


                                       16
<PAGE>

SECTION 18. DEFAULT

            The occurrence of any of the following shall constitute Tenant's
breach of and default under this Lease:

            (a)   The failure by Tenant to make any payment of Basic Annual
                  Rent, Additional Rent or pay other sums, taxes and insurance
                  premiums as and when due.

            (b)   Failure by Tenant in the prompt and complete performance and
                  observance of any other express or implied covenant, agreement
                  or obligation of Tenant contained in this Lease and the
                  continuation of such failure for a period of twenty (20) days
                  after notice thereof from Landlord to Tenant, provided,
                  however, that if the nature of Tenant's default is such that
                  more than twenty (20) days are reasonably required for its
                  cure, then Tenant shall not be deemed to be in default if
                  Tenant shall commence such cure within said twenty (20) day
                  period and thereafter diligently prosecute such cure to
                  completion.

            (c)   Any attachment or levy of execution or similar seizure of the
                  Premises or Tenant's fixtures or other property at the
                  Premises or any foreclosure, repossession or sale under any
                  chattel mortgage, security agreement or conditional sales
                  contract covering Tenant's fixtures or other property at the
                  Premises; or the filing by Tenant or any guarantor of this
                  Lease of, or consent to, any petition under any chapter of the
                  Bankruptcy Code or any state proceeding relating to insolvency
                  or protection from creditors, or the adjudication of Tenant or
                  of any guarantor of this Lease as a bankrupt or insolvent; or
                  the appointment of a receiver or trustee to take possession of
                  all or substantially all of the assets of Tenant or of any
                  guarantor of this Lease or a general assignment by Tenant or
                  of any guarantor of this Lease for the benefit of creditors;
                  or any other action taken or consented to by Tenant or by any
                  guarantor of this Lease under any state or federal insolvency
                  or bankruptcy act; or the involuntary filing of a bankruptcy
                  petition or state insolvency action by Tenant or any guarantor
                  of this Lease or appointment of a trustee or receiver for
                  Tenant or any guarantor of this Lease, and the same is not
                  dismissed or stayed within thirty (30) days.

            (d)   The vacation or abandonment of the Premises by Tenant.

SECTION 19. REMEDIES

            19.1 Landlord's Remedies. In the event of default by Tenant under
this Lease, Landlord may, at its option: (1) Terminate Tenant's right to
possession of the Premises because of such breach and recover from Tenant all
damages it may incur by reason of Tenant's default, including, without
limitation, the worth at the time of the award of the amount by which the unpaid
rent for the balance of the Lease Term after the time of award exceeds the
amount of such rental loss that Tenant proved could be reasonably avoided; or
(2) Not terminate Tenant's right to possession because of such breach, but
continue this Lease in full force and effect, in which event Landlord may
enforce all rights and remedies hereunder, including without limitation the
right to recover the Basic Annual Rent and Additional Rent as such becomes due.
In either event Landlord may reenter the Premises and remove all persons and
property from the Premises, storing said property in a public place, warehouse,
or elsewhere at the cost of, and for the account of, Tenant, all without service
of notice or resort to legal process and without being deemed guilty of or
liable in trespass. No such reentry or taking possession of the Leased Premises
by Landlord shall be construed as an election on its part to terminate this
Lease unless a written notice of such intention is given by landlord to Tenant.
No such action by Landlord shall be considered or construed to be a forcible
entry. In addition to, and not in lieu of, any of the remedies provided in this
Section 19.1, Landlord shall be entitled to take any other action and pursue any
other remedy provided at law, in equity or under this Lease. No reentry to,
taking possession of the Premises or other action by Landlord upon or following
the occurrence of any breach or default by Tenant shall be construed as an
election by Landlord to terminate this Lease unless Landlord provides Tenant
written notice of such termination.

            Should Landlord reenter, as provided above, or should it take
possession pursuant to legal proceedings or pursuant to any notice provided for
by Law, and whether or not it terminates this Lease, it may be necessary to
relet the Leased Premises. Landlord may relet the same or any part thereof for
such term or terms


                                       17
<PAGE>

(which may be for a term extending beyond the term of this Lease) and at such
rental or rentals and upon such other terms and conditions as Landlord in its
sole discretion may deem advisable. Upon each such reletting all rentals
received by the Landlord from such reletting shall be applied, first, to the
payment of any costs and expenses of such reletting, including brokerage fees
and attorney's fees and costs of any alterations and repairs; second, to the
payment of any indebtedness other than rent due hereunder from Tenant to
Landlord; third, to the payment of rent due and unpaid hereunder, and the
residue, if any, shall be held by Landlord and applied in payment of future rent
as the same may become due and payable hereunder. If such rentals received from
such reletting during any month shall be less than that to be paid during such
month by Tenant hereunder, Tenant shall pay any such deficiency to Landlord.
Such deficiency shall be calculated and paid monthly.

            19.2 Assignment of Subrents. As additional security for Tenant's
performance of its obligations hereunder, Tenant hereby assigns to Landlord the
right to receive the rents, issues, profits or other payments received under a
transfer of rights or sharing of the Premises by Tenant, reserving unto Tenant
the right prior to any breach or default hereunder to collect and retain said
rents, issues and profits as they become due and payable. Nothing in this
Section 19.2 shall be construed as permitting any transfer of rights or sharing
of the Premises contrary to Section 16.

            19.3 Landlord's Cure of Tenant's Default. If at any time during the
term hereof Tenant fails, refuses or neglects to do any of the things herein
provided to be done by Tenant, Landlord shall have the right but not the
obligation to do the same, but at the cost and for the account of Tenant. The
amount of any money so expended or obligations so incurred by Landlord together
with interest thereon at the lesser of eighteen percent (18%) per annum or the
maximum interest rate permitted by law shall be repaid to Landlord immediately
upon demand therefor, and unless so paid shall be added to the next monthly
payment coming due hereunder and shall be payable as rent.

            19.4 Interest and Charges on Past Due Obligations. Any amount due
from Tenant to Landlord hereunder which is not paid when due shall bear interest
at the lesser of eighteen percent (18%) per annum or the maximum lawful rate of
interest from the due date until paid, unless otherwise specifically provided
herein. In addition to such interest, if an installment of Basic Annual Rent is
not paid within five (5) days after the same is due, a late charge equal to four
percent (4%) of the amount overdue or One Hundred Dollars ($100), whichever is
greater, shall be assessed.

SECTION 20. RULES AND REGULATIONS

            Tenant shall faithfully observe and strictly comply with the rules
and regulations set forth in Exhibit "E" hereto. Said rules and regulations may
be deleted, amended or supplemented by Landlord from time to time with such
other rules and regulations as Landlord may reasonably adopt for the safety,
care, and cleanliness of the Building and the Property and the facilities
thereof, or the preservation of good order therein. Landlord shall not be liable
to Tenant for violation by any other tenant in the Building of any such rules
and regulations, or for breach of any covenant or condition in any lease.
Landlord has not represented and is not hereby representing that all tenants in
the Building are or shall be bound to any part or all of such rules and
regulations.

SECTION 21. SURRENDER OF PREMISES

            Upon the expiration or sooner termination of the term of this Lease,
Tenant shall surrender the Premises in as good condition as when received,
reasonable wear and tear excepted, broom clean and free of trash and rubbish,
and free from all tenancies or occupancies by any person. Tenant shall remove
all trade fixtures, furniture, equipment and other personal property installed
in the Premises prior to the expiration or earlier termination of this Lease.
Tenant shall, at its own cost, completely repair any and all damage to the
Premises and the Building resulting from or caused by such removal. If Tenant
fails to remove such items upon the expiration of this Lease, the same shall be
deemed abandoned and shall become the property of Landlord. Landlord shall not
be deemed to have accepted any surrender of the Premises to Landlord prior to
the end of the Lease Term, unless Landlord has agreed and acknowledged, in
writing, that it has accepted such surrender.


                                       18
<PAGE>

SECTION 22. HOLDING OVER

            Should Tenant, with or without Landlord's written consent, hold over
after the expiration of this Lease, Tenant shall pay, in advance, monthly rent
at the rate of one hundred fifty percent (150%) of one month's Basic Annual
Rent, plus all Additional Rent provided by this Lease.

SECTION 23. NOTICES

            Any notice required or permitted to be given hereunder shall be in
writing and shall be deemed effective either upon personal delivery, or receipt
thereof when deposited in the United States mail, registered or certified
delivery, return receipt requested, addressed to the Tenant at the Premises or
to Landlord or Tenant at the location stated in Item 13 of the Basic Lease
Provisions. Either party may specify a different address for notice purposes in
the manner aforesaid. A copy of all notices to be given to Landlord hereunder
shall be concurrently transmitted by Tenant to any additional party hereafter
designated by a notice from Landlord to Tenant. Notwithstanding the foregoing,
if either party refuses to accept or sign the return receipt for any notice
tendered to it pursuant to this Section 23, such notice shall be deemed
effective when tendered.

SECTION 24. ESTOPPEL CERTIFICATES

            Landlord or Tenant shall, at any time and from time to time, upon
not less than ten (10) days' prior notice from the other party, execute,
acknowledge and deliver to the party requesting a statement in substantially the
form and substance as the Estoppel Certificate attached hereto as Exhibit "F",
plus other information reasonably requested by a potential purchaser or
mortgagee. Landlord's or Tenant's failure to deliver such statement within such
time shall, at the option of Landlord or Tenant, constitute a default under this
Lease and, in any event, shall be conclusive upon Landlord or Tenant that this
Lease is in full force and effect without modification except as may be
represented by Landlord or Tenant in any such certificate prepare by Landlord or
Tenant and delivered to Landlord or Tenant for execution.

SECTION 25. LIABILITY OF LANDLORD

            In the event of any transfer or transfers of Landlord's interest in
the Premises, other than a transfer for security purposes only, Landlord shall
be automatically relieved of any and all obligations and liabilities hereunder
from and after the date of such transfer, it being intended hereby that the
covenants and obligations contained in this Lease on the part of Landlord shall
be binding on Landlord only during and in respect of its ownership. The
transferee of Landlord's interest in this Lease shall be deemed automatically
without further agreement to have assumed all of Landlord's duties and
obligations hereunder. Tenant agrees to look solely to Landlord's estate and
interest in the Property for the satisfaction of any remedy of Tenant for the
collection of a judgment (or other judicial process) requiring the payment of
money by Landlord in the event of any default by Landlord hereunder, and no
other property or assets of Landlord or of any partner, officer, director,
shareholder, agent or employee of Landlord shall be subject to levy, execution
or other enforcement procedure for the satisfaction of Tenant's remedies under
or with respect to this Lease, the relationship of Landlord and Tenant
hereunder, or Tenant's use or occupancy of the Premises.

SECTION 26. LANDLORD'S INABILITY TO PERFORM

            This Lease and the obligations of Tenant hereunder shall not be
affected or impaired because Landlord is unable to fulfill any of its
obligations hereunder or is delayed in doing so, if such inability or delay is
caused by reason of the unavailability of materials, strike or other labor
troubles or any other cause beyond the reasonable control of Landlord. Landlord
shall not be deemed to be in default in the performance of any obligation
required to be performed by it hereunder unless and until it has failed to
perform such obligation within thirty (30) days after notice by Tenant to
Landlord specifying wherein Landlord has failed to perform such obligation;
provided, however, that if the nature of Landlord's obligation is such that more
than thirty (30) days are required for its performance, then Landlord shall not
be deemed to be in default if it shall commence such performance within such
thirty (30) day period and thereafter prosecute same to completion.


                                       19
<PAGE>

SECTION 27. ATTORNEYS' FEES

            If Landlord or Tenant initiates any action to enforce any provision
of this Lease as a result of any breach or default on the part of Landlord or
Tenant, the losing party shall pay to the prevailing party all costs and
expenses, including reasonable attorneys' fees, incurred therein by Landlord or
Tenant.

SECTION 28. GENERAL PROVISIONS

            28.1 Headings and Definitions. The Section headings contained in
this Lease are for convenience of reference only and do not in any way govern
the construction thereof. The terms "Landlord" and "Tenant" as used herein shall
include the plural as well as the singular, and the neuter shall include the
masculine and feminine genders. The words "person" and "persons" whenever used
shall include individuals, firms, associations and corporations.

            28.2 Covenants and Agreements - Time of the Essence. Each of
Tenant's covenants and agreements herein contained are independent and not
dependent on Landlord's performance of its obligations hereunder, and the time
of the performance of each is of the essence of this Lease.

            28.3 Successors and Assigns. All of the covenants, conditions and
provisions of this Lease shall be binding upon and shall inure to the benefit of
the parties hereto and their respective heirs, personal representatives,
successors and assigns, subject to Section 16 hereof.

            28.4 Interpretation. The language in all parts of this Lease shall
be in all cases construed simply according to its fair meaning, and not strictly
for or against Landlord or Tenant. Any provision of this Lease which shall prove
to be invalid, void or illegal shall in no way affect, impair or invalidate any
other provision hereof and such other provisions shall remain in full force and
effect. This Lease may be executed in any number of counterparts, each of which
shall be an original and all of which together shall constitute and be construed
as one and the same instrument. This Lease shall be governed by and construed in
accordance with the laws of the State of Utah. All Exhibits and addenda
referenced or attached hereto are incorporated herein by reference as though
fully set forth herein.

            28.5 Waiver and Default. No waiver by Landlord of any provision of
this Lease shall be deemed to be a waiver of any other provision hereof or of
any subsequent breach by Tenant of the same or any other provision. No delay on
the part of Landlord in exercising any of its rights hereunder shall operate as
a waiver of such rights or of any other right of Landlord, nor shall any delay,
omission or waiver on any one occasion be deemed a waiver of the same or any
other right on any other occasion, nor shall Landlord's receipt from Tenant of
any sum with knowledge of any breach by Tenant of any of its covenants hereunder
be deemed to be a waiver of such breach. Neither Landlord's failure to bill
Tenant for any rent or other sum payable hereunder as it becomes due hereunder,
nor its error in such billing or failure to provide any other documentation in
connection therewith, shall operate as a waiver of Landlord's right to collect
any such rent or other sum payable hereunder which may have at any time become
due hereunder in the full amount to which Landlord is entitled pursuant to the
terms and provisions hereof. Landlord's consent to or approval of any act by
Tenant requiring Landlord's consent or approval, including approvals under
Section 16, shall not be deemed to render unnecessary the obtaining of
Landlord's consent to or approval of any subsequent act of Tenant whether or not
similar to the act so consented to or approved. None of Landlord's agents shall
have any power to accept the keys to the Premises prior to the termination of
this Lease, and the delivery of the keys to any such employee shall not operate
as a termination of this Lease or a surrender or Landlord's acceptance of the
Premises.

            28.6 Entire Agreement: Amendments. This Lease and the exhibits and
any riders attached hereto constitute the entire agreement between the parties
hereto with respect to the subject matter hereof, and no prior agreement or
understanding pertaining to any such matter shall be effective for any purpose.
No provision of this Lease may be amended or supplemented except by an agreement
in writing signed by the party or parties to be bound thereby.

            28.7 Building Name. Landlord reserves the right to change the name
of the Building from time to time during the term of this Lease. Tenant shall
not be allowed to use the name, picture or representation


                                       20
<PAGE>

of the Building, or words to that effect, in connection with any business
carried on in the Premises or otherwise (except as Tenant's address) without the
prior written consent of Landlord.

            28.9 Brokers. In connection with this Lease, Tenant warrants and
represents that it has had dealings only with the Brokers specified in Item 10
of the Basic Lease Provisions and that it knows of no other person who is or
might be entitled to a commission, finder's fee or other like payment in
connection herewith and does hereby indemnify and agree to hold Landlord
harmless from and against any and all loss, liability and expenses including any
attorneys' fees that Landlord may incur should such warranty and representation
prove incorrect.

            28.10 No Option. The submission of this Lease by Landlord, its agent
or representative for examination or execution by Tenant does not constitute an
option or offer to lease the Premises upon the terms and conditions contained
herein or a reservation of the Premises in favor of Tenant, it being intended
hereby that this Lease shall only become effective upon the execution hereof by
Landlord and delivery of a fully executed counterpart hereof to Tenant.

            28.11 Corporate and Partnership Tenant. In the event Tenant is a
corporation or a partnership, the parties executing this Lease on behalf of
Tenant hereby covenant and warrant, individually and on behalf of Tenant, that
Tenant is duly organized and in good standing in the state of its incorporation
or organization and that all steps have been taken prior to the date hereof to
qualify Tenant to do business in Utah, that Tenant has duly authorized this
Lease by all requisite corporate or partnership action and that the persons
executing this Lease have been duly authorized by Tenant to do so on its behalf.

            28.12 Recordation of Lease. Neither this Lease nor any memorandum
hereof shall be recorded by Tenant.

            28.13 Multiple Parties. If there is more than one person, firm,
corporation, partnership or other entity comprising Tenant, then (i) the term
Tenant, as used herein, shall include all of such persons, firms, corporations,
partnerships and other entities; (ii) each and every provision in this Lease
shall be binding on each and every one of them; (iii) each of them shall be
jointly and severally liable hereunder; (iv) Landlord shall have the right to
join one or all of them in any proceeding or to proceed against them in any
order; and (v) Landlord shall have the right to release any one or more of them
without in any way prejudicing its right to proceed against the others.

            28.14 No Partnership. Landlord does not by this Lease, in any way or
for any purpose, become a partner or joint venturer of Tenant in the conduct of
its business or otherwise.

            28.15 Telecommunications Equipment and HVAC. At any time during the
Lease Term, subject to availability, Tenant may install and maintain, at
Tenant's sole cost and expense, telecommunication equipment and/or an HVAC unit
("HVAC") upon the roof of the Building, subject to the payment of the prevailing
Building rates for the same. Upon thirty (30) days prior notice from Tenant to
Landlord, Landlord shall designate areas on the roof of the Building or other
areas of the Property which Tenant may lease for the purpose of installation,
operation and maintenance of (I) the HVAC and (ii) a satellite antenna or other
broadcasting and receiving device and the telecommunications conduits, devices,
fibreoptics and electrical, coaxial and other connections necessary to connect
the transmission devices to the Premises (collectively, the "Telecommunication
Devices"). Tenant shall have the right to use the Building utilities located on
the roof of the Building for the operation of the Telecommunication Devices and
HVAC at Tenant's sole cost and expense. Tenant shall have the right to access
the Telecommunication Devices and HVAC upon reasonable prior written notice to
Landlord, during business hours and subject to Landlord's reasonable rules and
regulations. Upon the expiration or earlier termination of this Lease, or at
such time as Tenant elects to stop paying for the use of space for the
Telecommunication Devices and/or HVAC, Tenant shall remove, at its own cost and
expense, the Telecommunications Devices and HVAC and all related facilities
thereof. If Tenant shall fail to complete such removal and/or fail to repair any
damage caused thereby, Landlord may do so and charge the cost thereof to Tenant
as Additional Rent. The physical appearance and size of the Telecommunication
Devices and HVAC shall be subject to Landlord's reasonable approval and Landlord
may require Tenant to install screening around such equipment, at Tenant's sole
cost and expense, as reasonably designated by Landlord. All Telecommunication
Devices and the HVAC must be compatible with the Building's systems and shall
not impair window washing or the use of chiller units, the cooling tower or
emergency generator, elevator machine rooms, helipads, ventilation


                                       21
<PAGE>

shafts, if any, or any other parts of the Building. The plans and specifications
for the Telecommunication Devices and HVAC and all working drawings for the
installation of the Telecommunication Devices and HVAC shall be subject to the
reasonable prior written approval of Landlord and Tenant obtaining any and all
required permits and governmental approvals, at Tenant's sole cost and expense.
If Tenant elects to install Telecommunication Devices or HVAC, Tenant's
indemnity obligation and waiver set forth in Section 12 of this Lease shall also
cover the use and installation of the Telecommunication Devices and HVAC. In
addition, Tenant shall procure and maintain at Tenant's sole cost and expense,
such insurance, in addition to the Qinsurance required to be maintained by
Tenant under this Lease, in connection with the Telecommunication Devices as
reasonably determined by Landlord. The Telecommunication Devices and the HVAC,
and the installation thereof shall comply with all applicable laws.

Notwithstanding the proceeding, Landlord hereby agrees to provide upon the
commencement of this Lease, a suitable location for Tenant's back-up generator,
HVAC and conduit allowing Tenant to cross connect with the fiberoptic providers
on the Property.

LANDLORD:                                 TENANT:

PARKSIDE SALT LAKE CORPORATION            ADVANCED TELECOMMUNICATIONS, INC.

                                                                     PLEASE SIGN
                                                                       & DATE

By: /s/ [ILLEGIBLE]              RM       By: /s/ Satish C. Tiwari
    -------------------------------           ----------------------------------

Its: Asset Manager                        Its:       SATISH C. TIWARI
     ------------------------------                 V.P. ENGINEERING AND
                                                   NETWORK IMPLEMENTATION
                                             ADVANCED TELECOMMUNICATIONS, INC.
                                                 730 2ND AVE S. SUITE 1200
                                                   MINNEAPOLIS, MN 55402

Date: 1-11-2000                           Date: 12/30/1999
      -----------------------------             --------------------------------


                                       22
<PAGE>

                                   EXHIBIT "A"

                          LEGAL DESCRIPTION OF PROPERTY

PARCEL NO. 1

Beginning at the northwest corner of Lot 5, Block 56, Plat "A", Salt Lake City
Survey, and running thence east 231.00 feet; thence south 231.00 feet; thence
west 66.00 feet; thence south 99.00 feet; thence west 66.00 feet; thence north
50.33 feet; thence west 99.00 feet; thence north 279.67 feet to the point of the
beginning.

            Contains 64,713.33 sq. ft.
              or 1.4856 Acres

PARCEL NO. 2

Beginning at a point east 51.00 feet and south 154.00 feet from the northwest
corner of Lot 7, Block 56, Plat "A" Salt Lake City Survey, and running thence
south 64.83 feet; thence west 51.00 feet; thence south 61.67 feet; thence west
81.00 feet; thence 126.50 feet; thence east 132.00 feet to the point of
beginning.

            Contains 13.552.83 sq. ft
              or 0.3111 Acres


                                       23
<PAGE>

                                   EXHIBIT "B"
                          AS-BUILT DRAWING OF PREMISES

Floor(s): 3rd
Suite Number: 380

                               [GRAPHIC OMITTED]


                                       24
<PAGE>

                                   EXHIBIT "C"

                MEMORANDUM OF COMMENCEMENT DATE AND RENTABLE AREA

Commencement Date: _________________________________
Rentable Area: ____________________________________________ square feet
Basic Annual Rent: $_______________________________________ Year 1
                   $_______________________________________ Year 2
                   $_______________________________________ Year 3
                   $_______________________________________ Year 4
                   $_______________________________________ Year 5
                   $_______________________________________ Year 6
                   $_______________________________________ Year 7
                   $_______________________________________ Year 8
                   $_______________________________________ Year 9
                   $_______________________________________ Year 10

(LANDLORD AND TENANT HEREBY AGREE that, upon execution of this Exhibit "C", the
determination of "Rentable Area" set forth herein shall be binding upon the
parties throughout the term of the Lease, regardless of any discrepancies which
may be shown by subsequent measurements.)

LANDLORD:                              TENANT:

PARKSIDE SALT LAKE CORPORATION         ADVANCED TELECOMMUNICATIONS, INC.



By:___________________________         By:______________________________


Its:__________________________         Its:_____________________________


Date:_________________________         Date:____________________________


                                       25
<PAGE>

                                   EXHIBIT "D"

                               TENANT WORK LETTER

                                 PARKSIDE TOWER
                                 215 SOUTH STATE
                              SALT LAKE CITY, UTAH

This "Work Letter Agreement" shall set forth the terms and conditions relating
to the construction of certain tenant improvements in the Premises. All
references in this Work Letter Agreement to Sections of the Lease shall mean the
relevant portion of Sections 1 through 28 of that certain Office Building Lease
to which this Work Letter Agreement is attached as Exhibit "D" and of which this
Work Letter Agreement forms a part, and all references in this Work Letter
Agreement to Sections of "this Work Letter Agreement" shall mean the relevant
portion of Sections 1 through 6 of this Work Letter Agreement.

                                    SECTION 1

                                  BASE BUILDING

      1.1 Base Building. Landlord owns and, through its advisors, agents,
representatives and employees, operates the base building in which the Premises
is located (collectively, the "Base Building"). Except as otherwise specifically
provided in this Lease, Tenant shall and does hereby accept the Base Building in
its presently existing, as-is condition.

                                    SECTION 2

                               TENANT IMPROVEMENTS

      2.1 Tenant Improvement Allowance. Tenant shall be entitled to a one-time
tenant improvement allowance (the "Tenant Improvement Allowance") in the amount
of $10.00 per usable square foot of the Premises or $57,960.00 for the costs
relating to improvements made to the Premises (collectively, the "Tenant
Improvements"). In no event, however, shall Landlord be obligated to make
disbursements pursuant to this Work Letter Agreement in a total amount which
exceeds the Tenant Improvement Allowance. To the extent the Tenant Improvement
Allowance exceeds the cost of the Tenant Improvements, Landlord shall be
entitled to keep and retain that portion of the Tenant Improvement Allowance
that exceeds the Tenant Improvements and Tenant shall not be entitled to the
same. Additionally, all cost over and above the Tenant Improvement Allowance
shall be the sole responsibility of Tenant.

      2.2 Disbursement of the Tenant Improvement Allowance. Except as otherwise
set forth in this Work Letter Agreement and subject to Section 2.1 of this Work
Letter Agreement, the Tenant Improvement Allowance shall be disbursed by
Landlord upon the following: (i) substantial completion of the Tenant
Improvements, (ii) presentment of invoice(s) from Tenant, and (iii) lien waivers
from all contractors and/or subcontractors. The Tenant Improvement Allowance
shall be for costs related to the Tenant Improvements and for the "Landlord
Supervision Fee," as that term is defined in Section 4.3.2 of this Work Letter
Agreement (collectively, the "Tenant Improvement Allowance Items").

                                    SECTION 3

                              CONSTRUCTION DRAWINGS

      3.1 Selection of Architect/Construction Drawings. Tenant shall retain the
architect/space planner designated by Landlord (the "Architect") to prepare the
"Construction Drawings," as that term is defined in this Section 3.1. Tenant
shall retain the engineering consultants designated by Landlord (the
"Engineers") to prepare all plans and engineering working drawings relating to
the structural, mechanical, electrical, plumbing, HVAC, lifesafety, and
sprinkler work of the Tenant Improvements. The plans and drawings to be prepared
by Architect and the Engineers hereunder shall be known collectively as the
"Construction Drawings." All Construction Drawings shall comply with the drawing
format and specifications as determined by Landlord, and shall be subject to
Landlord's approval, which shall not be unreasonably withheld or delayed. Tenant
and Architect shall verify, in the field, the dimensions and conditions as shown
on the relevant portions of the base Building


                                       26
<PAGE>

plans, and Tenant and Architect shall be solely responsible for the same, and
Landlord shall have no responsibility in connection therewith. Landlord's review
of the Construction Drawings as set forth in this Section 3, shall be for its
sole purpose and shall not imply Landlord's review of the same, or obligate
Landlord to review the same, for quality, design, Code compliance or other like
matters. Accordingly, notwithstanding that any Construction Drawings are
reviewed by Landlord or its space planner, architect, engineers and consultants,
and notwithstanding any advice or assistance which may be rendered to Tenant by
Landlord or Landlord's space planner, architect, engineers, and consultants,
Landlord shall have no liability whatsoever in connection therewith and shall
not be responsible for any omissions or errors contained in the Construction
Drawings, and Tenant's waiver and indemnity set forth in this Lease shall
specifically apply to the Construction Drawings.

      3.2 Final Space Plan. Tenant and the Architect shall prepare the final
space plan for Tenant Improvements in the Premises (collectively, the "Final
Space Plan"), which Final Space Plan shall include a layout and designation of
all offices, rooms and other partitioning, their intended use, and equipment to
be contained therein, and shall deliver the Final Space Plan to Landlord for
Landlord's approval, which shall not be unreasonably withheld or delayed

      3.3 Final Working Drawings. Tenant, the Architect and the Engineers shall
complete the architectural and engineering drawings for the Premises, and the
final architectural working drawings in a form which is complete to allow
subcontractors to bid on the work and to obtain all applicable permits
(collectively, the "Final Working Drawings") and shall submit the same to
Landlord for Landlord's approval, which shall not be unreasonably withheld or
delayed

      3.4 Permits. The Final Working Drawings shall be approved by Landlord (the
"Approved Working Drawings") prior to the commencement of the construction of
the Tenant Improvements. "Contractor" as identified in Section 1 above and as
that term is defined in Section 4.1 below, shall immediately submit the Approved
Working Drawings to the appropriate municipal authorities for all applicable
building permits necessary to allow Contractor, to commence and fully complete
the construction of the Tenant Improvements (the "Permits") and, in connection
therewith, Contractor shall coordinate with Landlord in order to allow Landlord,
at its option, to take part in all phases of the permitting process and shall
supply Landlord, as soon as possible, with all plan check numbers and dates of
submittal and obtain the Permits. Notwithstanding anything to the contrary set
forth in this Section 3.4, Tenant hereby agrees that neither Landlord nor
Landlord's consultants shall be responsible for obtaining any building permit or
certificate of occupancy for the Premises and that the obtaining of the same
shall be Contractor's responsibility; provided however that Landlord shall, in
any event, cooperate with Contractor in executing permit applications and
performing other ministerial acts reasonably necessary to enable Contractor to
obtain any such permit or certificate of occupancy. No changes, modifications or
alterations in the Approved Working Drawings may be made without the prior
written consent of Landlord, which shall not be unreasonably withheld or delayed

                                    SECTION 4

                    CONSTRUCTION OF THE TENANT IMPROVEMENTS

      4.1 Contractor. Tenant shall select one (1) or more contractors (the
"Bidding Contractors") from the list of approved contractors provided Tenant by
Landlord, to bid or quote on the construction of the Tenant Improvements.

      4.2 Cost Proposal. Tenant shall solicit bids or quotes from the Bidding
Contractors for the construction of the Tenant Improvements, which cost
proposals or quotations shall include, as nearly as possible, the cost of all
Tenant Improvement Allowance Items to be incurred by Tenant in connection with
the construction of the Tenant Improvements. Tenant shall approve and select the
cost proposal(s) or quotations (collectively, "Cost Proposal(s)") of the Bidding
Contractor(s) whom Tenant elects to retain to construct the Tenant Improvements
("Contractor(s)") and Tenant shall deliver originals or copies of the selected
Cost Proposal(s) and notice of its selection of the Contractor(s) to Landlord
within five (5) business days of the receipt of the cost proposals. Thereafter,
Tenant shall be released to purchase the items set forth in the Cost Proposal(s)
and to commence the construction relating to such items.

                  4.3.2 Tenant's Retention of Contractor. Tenant shall
independently retain the Contractor(s), to construct the Tenant Improvements and
Landlord shall supervise the construction by the Contractor(s), and Tenant


                                       27
<PAGE>

shall pay (and/or the Tenant Improvement Allowance shall be charged) a
construction supervision and management fee ("Landlord Supervision Fee") to
(and/or for) Landlord in an amount equal to the product of (i) five (5%) percent
of the Tenant Improvements.

Contractor's Warranties and Guaranties. Tenant hereby waives all claims against
Landlord relating to, or arising out of the construction of, the Tenant
Improvements.

                  4.3.4 Tenant's Covenants. Tenant hereby indemnifies Landlord
for any loss, claims, damages or delays arising from the actions of Architect on
the Premises or in the Building. Within ten (10) days after completion of
construction of the Tenant Improvements, Tenant shall cause Contractor and
Architect to cause a Notice of Completion to be recorded in the office of the
County Recorder of the county in which the Building is located in accordance
with any successor statute and furnish a copy thereof to Landlord upon
recordation, failing which, Landlord may itself execute and file the same on
behalf of Tenant as Tenant's agent for such purpose. In addition, immediately
after the Substantial Completion of the Premises, Tenant shall have prepared and
delivered to the Building a copy of the "as built" plans and specifications in
reproducible form (including all working drawings) for the Tenant Improvements.

                                    SECTION 5

                                  MISCELLANEOUS

      6.1 Tenant's Lease Default. Notwithstanding any provision to the contrary
contained in this Lease, if an event of default as described in Section 18 of
the Lease, or a default by Tenant under this Work Letter Agreement, has occurred
at any time, then (i) in addition to all other rights and remedies granted to
Landlord pursuant to the Lease, Landlord shall have the right to withhold
payment of all or any portion of the Tenant Improvement Allowance and/or
Landlord may cause the Contractor(s) to cease the construction of the Premises,
and (ii) all other obligations of Landlord under the terms of this Work Letter
Agreement shall be forgiven until such time as such default is cured pursuant to
the terms of the Lease.

LANDLORD:                                 TENANT:

PARKSIDE SALT LAKE CORPORATION            ADVANCED TELECOMMUNICATIONS, INC.

                                                                     PLEASE SIGN
                                                                       & DATE

By: /s/ [ILLEGIBLE]              RM       By: /s/ Satish C. Tiwari
    -------------------------------           ----------------------------------

Its: Asset Manager                        Its:       SATISH C. TIWARI
     ------------------------------                 V.P. ENGINEERING AND
                                                   NETWORK IMPLEMENTATION
                                             ADVANCED TELECOMMUNICATIONS, INC.
                                                 730 2ND AVE S. SUITE 1200
                                                   MINNEAPOLIS, MN 55402

Date: 1-11-2000                           Date: 12/30/1999
      -----------------------------             --------------------------------


                                       28
<PAGE>

                    Standard Building Specifications/Finishes

I.    PARTITIONS

      A.    Demising Partitions:
            1.    3 5/8" - 25 gauge metal studs at 16" on center.
            2.    5/8" drywall, one layer each side from floor slab to underside
                  of structure. (One hour fire rated assembly.)
            3.    3 1/2" - Batt insulation in wall cavity (R11 rating).
            4.    Partition to be taped and finished smooth to receive paint.
                  Penetrations through walls shall be sealed and openings shall
                  be fire rated as required by local building codes.
            5.    The end of the demising walls must occur at a building column
                  or at a vertical window mullions sealed off as detailed.

      B.    Interior Partitions:
            1.    3 5/8" - 25 gauge metal studs at 16" on center.
            2.    5/8" drywall, one layer each side floor to ceiling.
            3.    Partition to be taped and finished smooth ready to paint.
            4.    Interior partitions that end into glazing or vertical mullion
                  are to be finished as shown.
            5.    Partition height from floor to lay-in ceiling.
            6.    Options:
                  a.    Insulation - fiberglass, batt
                  b.    Insulation - sound attenuation, bat

II.   DOORS/FRAMES/HARDWARE

      A.    Corridor Door Assembly
            1.    Doors - Premium Grade - 3'-0" x 8'-4" x 1 3/4", 1/3 hour
                  rated.
                  a.    solid core, plain sliced red oak, matching hardwood
                        vertical edges.
                  b.    5-ply, 1/50" (min.) veneer, pre-machined
                  c.    Manufacturers: Algoma Hardwoods, Eggers. and Weyerhauser
            2.    Frames - 18 gage, 1/3 hour rated, hollow metal frames painted
                  to match stain finish color.
            3.    Side light - 2' wide per door leaf.

            4.    Glazing -
                  a.    1/4" wired glass. (Diamond or square pattern subject to
                        availability.)
                  b.    Size of glass as selected from standard door types.

            5.    Hinges -
                  a.    Two pairs of 4 1/2" x 4 1/2" ball bearing, butt hinges.
                  b.    Finish to match locksets.
                  c.    Hager 1279 or Stanley FBB 179.

            6.    Locksets -
                  a.    Schlage - Series "D"
                        (1)   Finish - (Choose one)
                              (a)   Satin chromium 626.
                              (b)   Bright Brass 605
                        (2)   Trim - (Choose one)
                              (a)   Knob - Orbit
                              (b)   Lever trim - Athens

            7.    Stops - Quality - Walls, 302 series, floor #431ES, finish to
                  match lockset
            8.    Door closer -
                  a.    Type Parallel arm.
                  b.    Finish - to match locksets


                                       29
<PAGE>

                  c.    Manufacture:
                        (1)   Sargent 1251-UO
                        (2)   Norton 7400 series.

            9.    OPTIONS:
                  a.    Additional corridor doors same as above, minimum. (Door
                        lite not required.)
                  b.    Dead bolts - Schlage Series "B400" 6-pin cylinder

      B.    Interior Door Assembly
            1.    Doors - Premium Grade, 3'-0" x 8'-4" x 1 3/4".
                  a.    Solid core, plain sliced red oak, matching hardwood
                        vertical edges
                  b.    5-ply 1/50" (mn.) veneer, pre-machined
                  c.    Manufactures: Algoma Hardwoods, Eggers, and Weyerhausers
            2.    1" (nominal) oak frame and casing stained and finished to
                  match doors.
            3.    Hinges -
                  a.    Two pairs of 4 1/2" x 4 1/2" butt hinges.
                  b.    Finish - to match lockset finish.
                  c.    Hager 1279 or Stanley FBB 179.
            4.    Latch/Trimset -
                  a.    Schlage - "MD" Designer series (Passage only - Roma)
                        (1)   Finish - Bright Brass 605
                        (2)   Locking function: Dead bolt
            5.    Stops - as manufactured by, Quality
                  a.    Walls - 302 series.
                  b.    Floor #431ES.
                  c.    Stainless steel finish.
            6.    Side Lite - 2' wide per door
            7.    OPTIONS:
                  a.    Door Closers
                        (1)   Type Parallel arm
                        (2)   Finish - to match lockset.
                        (3)   Sargent 125l-UO or Norton 7400 series.


                                       30
<PAGE>

III.  FINISHES:

      A.    Painting -
            1.    One coat of interior wall primer, tinted to match finish
                  color.
            2.    Two coats of satin interior alkyd paint applied with a roller.
            3.    Building standard colors. (Pratt & Lambert, Accolade interior
                  Semi-Gloss Latex, Calibrated Colors IV or equal).
      B.    Clear Finish Over Stained Wood -
            1.    Polyurathane, two coats on stained hardwood.
      C.    OPTIONS:
            1.    Wall Coverings
                  a.    Paneling - Solid wood stained to match color scheme.
                  b.    Vinyl Wall Covering - 13/oz/sq. yd. minimum.
                  c.    Fabric wall covering
                        (1)   100% Marquesa Lana.
                        (2)   13.2 oz/sq. yd. minimum.
                  d.    Others as approved by owner.

IV.   FLOOR COVERING
      A.    Carpet -
            1.    Weight - 36 oz minimum.
            2.    Style - Cut pile, 100% Techni-lon nylon.
            3.    10 year wear warranty.
            4.    Manufacturer - Charleston Carpets
                  a.    Belvedere.
                  b.    Harcourt.
            5.    Colors - See samples for Building Standard Colors Allowance:
      B.    Floor tile - (Reception, Lobby areas.)
            1.    12 x 12 x 3/8 marble, ceramic, or stone tiles.
      C.    Vinyl Composition Tile -
            1.    Manufacturer - Armstrong.
                  a.    Imperial
      D.    Option:
            1.    Carpet border
                  a.    Manufacturer and choices same as above.
            2.    Pad - 5.16" Steiner-Liff "Nova" pad, 6.5# per cubic foot.
            3.    Hardwood flooring - Type and color as approved.
            4.    Carpet accents or upgrades must meet or exceed minimum
                  requirement of standard as approved by owner.

V.    Base

      A.    Corridor -
            1.    4" stained hardwood to match elevator lobby stain color
            2.    4" cast stone to match elevator, Dal-Tile Granite
      B.    Tenant Space -
            1.    4" coved rubber by Roppe - continuous with pre-molded exterior
                  corners.
            2.    3 1/2" stained hardwood. (Corridors, conference rooms, etc.)
            3.    Options:
                  a.    4" marble or cast stone base.

VI.   ACOUSTIC CEILING

      A.    Ceiling height 8'-6".
      B.    Ceiling tile -
            1.    Omni Fissured.
            2.    5/8" X 2'x 2' mineral lay-in tiles.


                                       31
<PAGE>

            3.    Celotex or USG.
      C.    Acoustical suspension system -
            1.    Flat white by Donn Corp or equal.
      D.    OPTIONS:
            1.    Ceiling tile -
                  a.    Natural issured cast product.
                  b.    3/4" x 2' x 2' mineral lay-in tiles.
                  c.    Celotex or USG.
            2.    Sound attenuation tile blankets -

VII.  WINDOW COVERING

      A.    Levelor 1" Mini-Blinds, Color black.
      B.    OPTIONS:
            1.    Interior window covering.
                  a.    Mini-blinds - Levelor 1"
                  b.    Vertical - Levelor 4"
                  c.    Curtain Hardware -
                        (1)   "Super Fine" Kirsch Co.
                        (2)   601 Sanes Graber Industries, Inc.

VIII. CABINETS

      A.    OPTIONS:
            1.    Shelving and brackets. (Exposed to View)
                  a.    Stained hardwood plywood with solid hardwood edge.
            2.    Counter tops.
                  a.    Wilsonart horizontal grade color as approved by Owner.
                  b.    Edging shall be a manufactured hardwood edge as approved
                        by Owner.
            3.    Kitchen type cabinets.
                  a.    Interiors -
                        (1)   Prefinished plastic coated high density particle
                              board. (Kortron or approved equal.)
                        (2)   Stained plywood.
                        (3)   Parts exposed to view to match doors.
                                    b.    Doors -
                                    (1)   Stained solid hardwood.
                                    (2)   Plastic laminate faced millwork.

IX.  PLUMBING
      A.    OPTIONS:
      1.    Toilet Room.
            a.    Fixtures - shall be stainless steel.
      2.    Kitchen/Break Rooms
            a.    Sinks - shall be stainless steel.
            b.    Refrigerator
            c.    Microwave oven
            d.    Dishwasher
      3.    Piping -
            a.    Supply lines - as per state and local building codes.
            b.    Waste and vent lines - as per state and local building codes.

X.    FIRE SPRINKLERS

A.    Chrome semi-recessed heads. Installed per state and local codes.
B.    Escutcheons and trim shall be chrome to match existing.


                                       32
<PAGE>

XI.   HEATING & AIR CONDITIONING DISTRIBUTION

A.    Supply Air Diffusers - Slot type, clear anodized.
B.    Return Air Grille - 2'x 2' perforated grille, white.
C.    Thermostats, Distribution Duct Work - as per building standards
      throughout.

XII.  LIGHTING

A.    Light Fixtures
            1.    Corridors - Day-Brite, 2'x 2' fluorescent, 2 tube,
            Catalog #PGC222-P16S22-ESB, 277 Volts 100 Watts, energy efficient
                  lamps
                  F4OUT12WMII, lay in, return air troffer, 3" 16 cell paralouver
                  lens. (Match existing fixtures.)
            2.    Interior space - Day-Brite, 2'x 4' fluorescent, 4 tube,
                  Catalog #PGC424-ESB, 277 Volts 100 Watts, energy efficient
                  lamps F4OTI2WMII, lay in, return air troffer, 3" 32 cell
                  parlouver lens. (Match existing fixtures.)
            3.    Emergency lighting: Emergency generator system.
      B.    Accent Lighting
            1.    Down Light - Recessed down light with aluminum reflector with
                  black baffle, PL-13 double twin lamp, 277V, 6.5 aperture as
                  manufactured by - Halo H275-409P, Marco FM13-63-277 or
                  Prescolite CFX TO-76S-277.
            2.    Recessed down - Recessed 75W PAR38/3, gimbal ring adjustable,
                  as manufactured by Prescolite PBX-TA-72, or equal Halo, Marco.
      C.    Switch Assembly
            1.    Pass & Seymour 20AC series or equal, with smooth plastic
                  cover.
            2.    Color- Ivory.
      D.    Motion Detector
            1.    Hubbel - H-MOSS 1000 Wall Switch, WSS-1277, with off override
                  and 12 minute delay. (Model 257-151 SA for ceiling
                  applications.)
            2.    Use in lieu of standard switch assembly.
      E.    Exit Lights
            1.    Emergency generator system.
      F.    Installation - Contractor shall install electrical system as
            required per state and local codes.
      G.    Smoke Detection, Alarm & Communication Systems
            1.    Modify existing building systems per as per requirements of
                  the U.B.C. Section 1807 and ANS1A117.1-1996.
      H.    OPTIONS:
            1.    Track Lighting
                  a.    Two circuit track by Halo or Lightolier.
                  b.    Heads - Halo or Lightolier style as selected by tenant.

XII.  POWER -

      A.    Outlets
            1.    Duplex receptacle - Series 5342 (20 Amp) by Pass & Seymour or
                  equal with smooth plastic cover plate.
            2.    Color - Ivory.
      B.    OPTIONS:
            1.    Isolated Circuits. - Pass & Seymour 2091 (20 Amp) or equal,
                  orange, with ivory smooth plastic cover plate.
            2.    Floor Outlets - Model RC-700A as manufactured by Raceway
                  Components Inc., 208 19th avenue, Paterson, NJ 07524.


                                       33
<PAGE>

XIV.  TELEPHONE

      A.    Telephone Outlets - Empty single gang box with 3/4" conduit stubbed
            into ceiling space with blank ivory cover plate.
      B.    Service -
            1.    3/4" conduit from outlet to centrally located pull box or
                  telephone board.
      C.    OPTIONS:
            1.    Telephone equipment board - 3/4" plywood edges filled and
                  finished. Painted to match wall.
            2.    Communication cables must be plenum rated or be in conduit.
            3.    Standard modular telephone outlets as needed.


                                       34
<PAGE>

                                  EXHIBIT "F"

                             RULES AND REGULATIONS

1. The sidewalks, entrances, passages, courts, elevators, stairways, corridors
or halls shall not be obstructed or used for any purpose other than ingress or
egress.

2. No awnings or other projections shall be attached to the outside walls of the
Building.

3. The sashes, sash doors, skylights, windows and doors that reflect or admit
light and air into the halls, passageways or other public places in the Building
shall not be covered or obstructed, nor shall any bottles, parcels or other
articles be placed on the windowsills. If Tenant desires window curtains, the
same must be of such uniform shape, color, material and make as may be
prescribed by Landlord. Neither the interior nor the exterior of any windows
shall be coated or otherwise sunscreened without Landlord's prior written
consent.

4. No sign, advertisement or notice shall be exhibited, painted or affixed by
Tenant on any part of, or so as to be seen from the outside of, its Premises or
the Building without Landlord's prior written consent. In the event of Tenant's
violation of the foregoing, Landlord may remove the same without any liability
and may charge the expense incurred in such removal to Tenant. All signs,
whether on doors, directory tablets or elsewhere, shall be inscribed, painted or
affixed for Tenant by Landlord at the expense of Tenant, and shall be of a size,
color and style acceptable to Landlord. Landlord may prescribe a design standard
for all such signs.

5. The bulletin board or directory of the Building will be provided exclusively
for the display of the name and location of Tenant only; and Landlord reserves
the right to exclude any other names therefrom, and each and every name in
addition to the name of Tenant placed upon such bulletin board or directory,
shall be subject to Landlord's prior written consent (and if approved by
Landlord, all costs therefor shall be paid by Tenant). Any such listings or
representations, once installed, shall be subject to relocation or removal upon
Landlord's written request for any reason (except that any such relocations or
removals at Landlord's request, unless such request is based upon Tenant's
breach of the Lease, of which these Rules and Regulations are a part, shall be
paid for by Landlord), and Tenant shall pay for the removal of any such listings
or representations upon its departure from its Premises.

6. All doors opening into public corridors shall be kept closed, except when
being used for ingress and egress.

7. Tenant shall not mark, paint, drill or bore into, cut or string wires in, lay
linoleum or other floor coverings in, or in any way deface any part of its
Premises or the Building, except with Landlord's prior written consent and as
Landlord may direct.

8. All keys shall be obtained from Landlord and neither Tenant, its agents or
employees shall have any duplicate keys made. No additional locks or bolts of
any kind shall be placed upon any of the doors or windows by Tenant, nor shall
any changes be made in existing locks or the mechanisms thereof. Tenant must,
upon the termination of its tenancy, give to Landlord all keys pertaining to the
Premises and the Building, and in the event of the loss of any keys so
furnished, Tenant shall pay Landlord the cost of replacing same or of changing
the lock or locks opened by such lost key(s) if Landlord shall deem it necessary
to make such change.

9. No window or other air conditioning or heating units or other similar
apparatus shall be installed or used by Tenant without Landlord's prior written
consent. Tenant shall not be permitted upon the roof at any time.

10. The water and wash closets and other plumbing fixtures shall not be used for
any purpose other than those for which they were constructed and no sweepings,
rubbish, rags or other substances shall be thrown therein. All damages resulting
from any misuse of the fixtures by Tenant or its servants, employees, agents,
visitors or licensees shall be bone by Tenant.


                                       35
<PAGE>

11. All removals from, or the carrying in or out of, the Building of any safes,
freight, furniture, heavy or bulky matter of any description, must take place
only between the hours of 9:00 and 11:00 A.M., and 2:00 and 4:00 P.M. of days
other than Saturdays, Sundays and holidays (no moving being permitted on
Saturdays, Sundays or holidays without special permission) and must be made upon
previous written notice to Landlord and under its supervision, and the persons
employed by Tenant for such work must be acceptable to Landlord. Landlord
reserves the right to inspect all safes or other heavy or bulky equipment or
articles to be brought into the Building and to exclude from the Building all
such heavy or bulky equipment or articles, the weight of which may exceed the
floor load for which the Building is designed, or such equipment or articles as
may violate any of the provisions of the Lease of which these Rules and
Regulations are a part. Tenant shall not use any machinery or other bulky
articles in the Premises, even though its installation may have been permitted,
which may cause any noise, or jar, or tremor to the floors or walks, or which by
its weight might injure the floor of the Building.

12. Neither Tenant nor its servants, employees, agents, visitors or licensees
shall at any time bring or keep upon the Premises any flammable, combustible or
explosive fluid, chemical or substance.

13. The Premises shall not be used for manufacturing or for the storage of
merchandise except as such storage may be incidental to the permitted use of the
Premises. Tenant shall not, without Landlord's prior written consent, occupy or
permit any portion of the Premises to be occupied or used for the manufacture or
sale of liquor or tobacco in any form, or as a barber or manicure shop, or as an
employment bureau. The Premises shall not be used for lodging or sleeping. No
sales or auctions shall be conducted from the Premises.

14. Tenant shall not make, or permit to be made, any unseemly or disturbing
noises, or disturb or interfere with occupants of the Building or neighboring
buildings or premises or these having business with it by the use of any musical
instrument, radio, phonographs or unusual noise, or in any other way. Neither
Tenant nor its servants, employees, agents, visitors or licensees shall throw
anything out of doors, windows or skylights or down the passageways.

15. No bicycles, vehicles, birds or animals of any kind shall be brought into or
kept in or about the Premises or the Building and no cooking shall be done or
permitted by Tenant in its Premises, except that the preparation of coffee, tea,
hot chocolate and similar items and items that can be heated in a microwave oven
for Tenant, its employees and visitors shall be permitted provided such
activities do not otherwise violate the Lease of which these Rules and
Regulations are part and provided power shall not exceed that amount which can
be provided by a 30 amp circuit. Tenant shall not cause or permit any unusual or
objectionable odors to be produced in or emanate from the Premises.

16. There shall not be used in any space, or in the public halls of the
Building, any hand truck except those equipped with rubber tires and side
guards.

17. No vending or coin operated machines shall be placed within the Premises
without Landlord's prior written consent.

18. No person shall be employed by Tenant to do janitorial work in any part of
said Building without Landlord's prior written consent. Any person employed by
Tenant to do janitorial, maintenance or similar work with Landlord's consent
shall, while in the Building, be subject to and under the control and direction
of Landlord or its agent or representative (but not as an agent or servant of
Landlord) and Tenant shall be responsible for all acts of such persons.

19. Landlord shall have the right to prohibit any advertising by Tenant which,
in Landlord's opinion, tends to impair the reputation of the Building or its
desirability as an office building, and upon written notice from Landlord,
Tenant shall refrain from or discontinue such advertising.

20. Canvassing, soliciting and peddling in the Building are prohibited and
Tenant shall cooperate to prevent same.

21. Landlord reserves the right to control access to the Building by all persons
after reasonable hours of generally recognized business days and at all hours on
Sundays and legal holidays. Tenant shall be responsible for all persons for whom
it requests after-hours access and shall be liable to Landlord for all acts of
such persons.


                                       36
<PAGE>

Landlord assumes no responsibility and shall not be liable for any damage
resulting from the admission of any unauthorized person to the Building. Upon
request Tenant shall provide Landlord with a description and license plate
number of all its personnel's vehicles utilizing parking at the Building.

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

23. It is understood and agreed between Landlord and Tenant that no assent or
consent to any waiver or any part hereof by Landlord in spirit or letter shall
be deemed or taken as made except if same is done in writing and attached to or
endorsed hereon by Landlord.

24. Landlord reserves the right at any time to change or rescind any one or more
of these Rules or Regulations, or to make such other and further reasonable
Rules and Regulations as in Landlord's judgment may from time to time be
necessary for the management, safety, care and cleanliness of the Premises,
Building and Common Areas, and for the preservation of good order therein, as
well as for the convenience of other occupants and tenants therein. Landlord
shall not be responsible to Tenant herein or to any other person for the
nonobservance of the Rules and Regulations by any other tenant or other person.
Tenant shall be deemed to have read these Rules and Regulations and to have
agreed to abide by them as a condition to its occupancy of the Premises.


                                       37
<PAGE>

                                  EXHIBIT "F"

                         TENANT'S ESTOPPEL CERTIFICATE

The undersigned, as Tenant, under that certain Office Lease (the "Lease") dated
as of ________, 19__ made with Parkside Salt Lake Corporation, a Delaware
corporation, as Landlord, hereby certifies as follows (all initially capitalized
terms or phrases used herein shall have the same meanings as in the Lease):

            1. The undersigned entered into occupancy of the Premises described
in the Lease on ______________________, 19__;

            2. The undersigned opened for business in the Premises on _______,
19__;

            3. The Lease (including all Exhibits) is in full force and effect
and has not been assigned, modified, supplemented or amended in any way, except
as follows: _______________________________________

            4. The Lease, as affected by those changes set forth in Paragraph 3
above, represents the entire agreement between the parties as to the Premises;

            5. The Commencement Date under the Lease was _________________;

            6.The term of the Lease will expire on _______________________;

            7. All conditions of the Lease to be performed by Landlord and
necessary to the enforceability of the Lease have been satisfied;

            8. There are no uncured defaults by Landlord or Tenant under the
Lease and Tenant knows of no events or conditions which with the passage of time
or notice or both, would constitute a default by Landlord or Tenant under the
Lease, except as follows:

            9. No rents have been prepaid, other than for the current month and
as expressly provided in the Lease;

            10. As of the date hereof, the undersigned has no existing defenses
against or offsets of Basic Annual Rent or Additional Rent or the enforcement of
the Lease by Landlord;

            11. The total amount of security deposit delivered to Landlord is
$_______ , and none of that amount has, to Tenant's knowledge, been applied by
Landlord to cure any default by Tenant; and

            12. The current monthly installment of Basic Annual Rent is
_____________, and has been paid through _____________, 19__.


            EXECUTED this ______ day of _________, 19__.

            "TENANT"

            By:____________________________________

            Its:___________________________________


                                       38
<PAGE>

                                  EXHIBIT "G"

                               PARKING PROVISIONS

            1. Capitalized terms used but not defined in this Exhibit shall have
the meanings ascribed to them in the Office Lease (the "Lease") to which this
Exhibit is attached.

            2. Subject to the terms and conditions of this Exhibit, Landlord
shall issue Tenant parking passes (individually, a "Pass" and collectively, the
"Passes") for the parking facilities owned by Landlord in connection with the
Building (the "Facilities") in such numbers as Tenant may request, up to the
maximum number of thirteen (13) Passes for unreserved parking outstanding to
Tenant at any given time. Unreserved parking shall be designated as parking in
the parking garage rather or the surface parking lot both of which constitute
part of the Facility. Each Pass shall, during the time it is in effect, entitle
Tenant to park one vehicle in the type of parking stall designated in the Pass;
provided Passes for unreserved parking shall be subject to the availability of
parking spaces. Tenant acknowledges that in order for Landlord to fully utilize
the Facilities, and to facilitate the providing of parking to clients and
visitors of tenants of the Building, Landlord will make estimates and
predictions as to the numbers of Passes for unreserved parking that will be used
on each day and at any given time, and permit others to use the Facilities based
upon such estimates and predictions. On occasion, and from time to time,
unanticipated usage of the Facilities may result in parking spaces being
unavailable for the holders of Passes for unreserved parking. If, however, on a
frequent and recurring basis, there are no unreserved parking spaces available
to the holders of Tenant's Passes for unreserved parking, Landlord will, at
Tenant's written request, make reasonable adjustments to Landlord's parking
policies and practices in order to limit the occurrence of such problems to an
occasional basis.

            3. Prior to the first day of each month, Tenant shall pay Landlord
the monthly parking fee of $55.00 per Pass for unreserved Passes, subject to
periodic market adjustments, for each Pass that will be outstanding to Tenant
during such month. If such fee is not paid when due with respect to any Pass,
such Pass shall immediately become null and void and Tenant shall promptly
return such Pass to Landlord. Landlord may, in its discretion, increase such
fees at any time and from time to time so long as the fees charged for the
Passes are reasonably competitive with rates being charged at the time for
similar parking in the general area of the Building.

            4. Tenant's rights under this Exhibit shall terminate and Tenant
shall promptly return to Landlord all outstanding Passes issued to it upon the
occurrence of either of the following: (i) the last day of the Lease Term; or
(ii) any default or breach on the part of Tenant under the Lease or this
Exhibit.

            5. The parking rights granted to Tenant under this Exhibit or under
the Passes shall be deemed a license only and nothing in this Exhibit or the
Passes shall be construed as granting to or vesting in Tenant any fee, leasehold
or other interest in the Facilities other than a license which is subject to
termination as provided in this Exhibit.

            6. Landlord's inability to make parking available at any time to
holders of the Passes shall not be deemed to be a breach or default on the part
of Landlord under the Lease or under this Exhibit so long as such inability is
due to fire, flood, earthquake, strikes, riots, blackouts, condemnation and
other casualties or causes reasonably beyond Landlord's control. The abatement
of Tenant's obligation to pay parking fees for the Passes during any such period
for which parking is unavailable shall constitute Tenant's sole remedy in the
event of such unavailability.

            7. Tenant may permit its personnel to use Passes issued to Tenant
pursuant to this Exhibit, provided Tenant shall maintain on file with Landlord
at all times a current list of each of Tenant's personnel permitted to use a
Pass. Only one of Tenant's personnel at any given time shall be assigned to a
given Pass and only that person may use such Pass. Tenant shall be fully
responsible to Landlord to assure that each of Tenant's personnel whom Tenant
permits to use a Pass fully complies with the terms and conditions of this
Exhibit and shall be liable to Landlord for any failure of any of Tenant's
personnel to so comply. Landlord may deal directly with those persons designated
by Tenant as authorized to use the Passes with regard to such matters as the
renewal of


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<PAGE>

Passes and the collection of monthly parking fees, and no such direct dealings
shall relieve Tenant of any of its duties or obligation hereunder.

            8. Except as provided in Section 7 above, Tenant shall not assign
any of its rights under this Exhibit other than in connection with a permitted
sublease or assignment under the Lease. Any assignment by Tenant contrary to the
terms of this Exhibit shall be of no force or effect.

            9. In connection with the use of the Facilities, Tenant shall
observe and comply with, and shall cause each person who uses any Pass issued to
Tenant under this Exhibit to observe and comply with, all rules and regulations
promulgated by Landlord, as in effect from time to time with respect to the use
of the Facilities, including, without limitation, rules and regulations
regarding spaces or areas in which parking is restricted, limited or prohibited.
If Tenant or any person using any of Tenant's Passes fails to observe such rules
and regulations, Landlord, at its sole option, may, in addition to any other
remedy it may have, cancel Tenant's rights under this Exhibit and require Tenant
to relinquish all Passes issued to it.

            10. By using the Facilities, Tenant and all persons using Passes
issued to it accept and assume all risk of injury caused by any other users of
the Facilities and of damage, loss or theft of any vehicle or other property
while in the Facilities.

            11. Landlord, at its sole option, shall have the right to move the
locations of reserved parking stalls and to assign designated parking stalls
with respect to Passes for unreserved parking at any time during the term of
this Exhibit.

            12. Tenant's use of the Facilities as herein set forth shall be in
common with other tenants of the Building and any other parties permitted by
Landlord to use the Facilities.

            13. Any breach or default by Tenant under this Exhibit shall
constitute a default on the part of Tenant under the Lease and any breach or
default by Tenant under the Lease shall constitute a default on the part of
Tenant under this Exhibit. If Landlord elects to terminate the License pursuant
to Section 3 of this Exhibit because of a breach or default by Tenant under this
Exhibit, Landlord may, at its discretion, exercise any or all remedies allowed
under the Lease or applicable law.

            14. Nothing in this Exhibit shall be deemed to alter, modify,
release, nullify or reduce, in any manner whatsoever, Tenant's obligations under
the Lease. Tenant shall comply with the Building Rules and Regulations attached
to the Lease in connection with the exercise of its rights under this Exhibit.
Except where the provisions of this Exhibit directly contradict the Lease, the
provisions of the Lease shall apply to this Exhibit and any provision of the
Lease which provides greater protection to Landlord than is provided under this
Exhibit may, at Landlord's discretion, be applied to any dispute or issue
regarding this Exhibit.


LANDLORD:                                 TENANT:

PARKSIDE SALT LAKE CORPORATION            ADVANCED TELECOMMUNICATIONS, INC.

                                                                     PLEASE SIGN
                                                                       & DATE

By: /s/ [ILLEGIBLE]              RM       By: /s/ Satish C. Tiwari
    -------------------------------           ----------------------------------

Its: Asset Manager                        Its:       SATISH C. TIWARI
     ------------------------------                 V.P. ENGINEERING AND
                                                   NETWORK IMPLEMENTATION
                                             ADVANCED TELECOMMUNICATIONS, INC.
                                                 730 2ND AVE S. SUITE 1200
                                                   MINNEAPOLIS, MN 55402

Date: 1-11-2000                           Date: 12/30/1999
      -----------------------------             --------------------------------


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