<PAGE>
                                                                   EXHIBIT 10.29

                                iTRACS SUBLEASE

     THIS SUBLEASE (the "Sublease") is executed this 27th day of February, 2001,
by and between Integrated Information Systems, Inc., a Delaware corporation
("Sublandlord"), and iTRACS Corporation, a Delaware corporation ("Subtenant").

RECITALS:

     A.   Sublandlord, as "Tenant," and AmberJack, Ltd. ("Master Landlord"), as
"Landlord," previously entered into that certain Lease and Lease Addendum dated
December 8, 1998, a copy of which is attached hereto as Exhibit D (the "Master
Lease"), pursuant to which, Master Landlord leased to Sublandlord certain
premises more particularly described therein.

     B.   Subtenant desires to sublease the western portion of the Master Lease
premises identified as "Suite 190" and described more completely in Section 3(k)
below (the "Premises") from Sublandlord on the terms and conditions hereinafter
set forth.

     NOW, THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which is hereby acknowledged, the parties agree as follows:

                                   AGREEMENT

     1.  Sublease. Sublandlord hereby leases to Subtenant, and Subtenant hereby
         leases from Sublandlord, the Premises commencing on the Commencement
         Date and expiring on the Expiration Date, each as respectively defined
         in Sections 3(f) and 3(g) (the "Term"), at the rental and upon all the
         covenants set forth herein.

     2.  Master Lease. Except as may be inconsistent with the terms of this
         Sublease, all of the terms, covenants and conditions contained in the
         Master Lease are hereby incorporated by this reference into, and made a
         part of, this Sublease, and shall be applicable with the same force and
         effect as if Sublandlord were the "Landlord" under the Master Lease and
         Subtenant were the "Tenant" thereunder. In this regard, Subtenant
         hereby assumes, covenants and agrees with Sublandlord to perform and be
         bound by and subject to all of the terms and conditions contained in
         the Master Lease to be performed by the "Tenant" thereunder or by which
         the "Tenant" is bound under the Master Lease as the same relate to the
         Premises. Sublandlord does not assume the obligations of the Master
         Landlord under the provisions of the Master Lease, but shall exercise
         due diligence in attempting to cause Master Landlord to perform its
         obligations under the Master Lease for the benefit of Subtenant.
         Sublandlord grants Subtenant the right at its option, to enforce
         Sublandlord's rights under the Master Lease as they affect or relate to
         the Premises. If any of the express provisions of this Sublease
         conflict with the terms of the Master Lease, such conflict shall be
         resolved in favor of the express provisions of this Sublease.

<PAGE>



3. Basic Lease Provisions.

      a.  Building Property Address: 1501 West Fountainhead Parkway,  Tempe,
             Arizona, 85282.

      b.  Sublandlord's Address for Notices: Integrated Information Systems,
          Inc., 1560 West Fountainhead Parkway, Suite 200, Tempe, Arizona,
          85282, Attention: Legal Department, with a copy to Snell & Wilmer,
          L.L.P., One Arizona Center, Phoenix, Arizona, 85004-2202, Attention:
          Sharon Fabian, Esq.

      c.  Subtenant's Address for Notices: 1501 West Fountainhead Parkway, Suite
          190, Tempe, Arizona, 85282, Attention: John Reedy. Copy to Jenner and
          Block 330 North Wabash, 40th Floor, 1 IBM Plaza, Chicago, IL, 60611,
          Attention: Craig R. Culbertson.

      d.  Master Landlord: AmberJack, Ltd.

      e.  Master Landlord's Address for Notices: c/o Birtcher Arizona, 2400
          South 55th Street, Tempe, Arizona, 85282.

      f.  Commencement Date: April 1, 2001.

      g.  Expiration Date: 11:59 p.m. on July 31, 2003.

      h.  Base Rent:

                     Time Period              Monthly         Annual Rent per
                                               Rent                RSF

               April 1, 2001-May 31, 2001       $0                 $0
               June 1, 2001-December 31, 2001 $18,650            $20.00
               January 1, 2002-July 31, 2003  $20,515            $22.00

      i.  Payee of Rent: Integrated Information Systems, Inc.

      j.  Address for Payment of Rent: 1560 West Fountainhead Parkway, Suite
          200, Tempe, Arizona, 85282, Attention: Accounting Department.

      k.  Description of Premises: The premises covered by this Sublease consist
          of approximately 11,190 rentable square feet of space of the first
          floor of the building (Suite 190) located at the address set forth in
          (a) above (the "Building") as shown on Exhibit A hereto (the
          "Premises").

      l.  Subtenant's Percentage Share of Building Operating Expenses: 6.93%

      m.  Security Deposit: $18,650.


                                      -2-









<PAGE>

4.  Signage. Subtenant shall have the right to place a sign behind the reception
    desk and signs on the two main doors accessing the Premises identifying the
    Subtenant's business.

5.  Parking. Subtenant shall at all times during the Term of this Sublease have
    the right to use and occupy 31 covered reserved parking spaces, all located
    in the parking facilities adjacent to the Premises and identified on
    Exhibit B attached hereto and made part hereof, at no additional cost or
    expense to the Subtenant.

6.  Right to Examine. At any time and from time to time, Subtenant may examine
    the books and records of Sublandlord relating to the Premises and the
    leased premises subject to the Master Lease. Sublandlord agrees to make
    such books and records available to Subtenant at Sublandlord's premises
    which are subject to the Master Lease.

7.  Rent. Subtenant agrees to pay all rents and other charges owed to
    Sublandlord pursuant to this Sublease to Sublandlord at its notice address
    as set forth in Paragraph 3(b) hereof, Attention: Accounting Department.
    Subtenant agrees to pay all sales, rental and/or transaction privilege
    taxes on the rents and charges (except for Sublandlord's income or similar
    tax) now or hereafter imposed by any taxing authority upon Sublandlord's
    receipt of Base Rent from Subtenant pursuant to this Sublease. Any charges
    due and payable under this Section 7 or as elsewhere provided in this
    Sublease which are not Base Rent payments shall be considered additional
    rent. Notwithstanding anything to the contrary contained herein or in the
    Master Lease, Sublandlord shall pay all Operating Expenses (as defined in
    the Master Lease) with respect to the Premises for, through and including
    calendar year 2001. Commencing January 1, 2002, Subtenant shall pay its
    Percentage Share, as defined in Section 3 (1), of Building Operating
    Expenses in excess of the actual Building Operating Expenses for calendar
    year 2001. If Sublandlord provides Subtenant with written notice of an
    estimate, calculated using commercially reasonable judgment, of such amount
    for the upcoming calendar year, Subtenant shall pay 1/12th of such amount
    each month at the same time Subtenant pays its Base Rent. Within ninety (90)
    days following the expiration of each such calendar year, Sublandlord
    shall provide Subtenant with a reconciliation of actual Building Operating
    Expenses as compared to the estimated Building Operating Expenses and the
    2001 base year Building Operating Expenses. In the event Subtenant made
    an overpayment, Sublandlord shall promptly refund Subtenant such amount. In
    the event of an underpayment, Subtenant shall pay such discrepancy by the
    later of (i) thirty (30) days after reconciliation thereof, or (ii) the
    next due date for Base Rent. Sublandlord agrees to deliver any and all
    estimates and statements regarding Operating Expenses received from Master
    Landlord within two (2) days after Sublandlord's receipt thereof.

8.  Security Deposit. Concurrently with Subtenant's execution of this Sublease,
    Subtenant shall deposit with Sublandlord a cash sum in the amount stated in
    Section 3(m) of the Basic Lease Provisions (the "Security Deposit").
    Sublandlord shall hold the Security Deposit as security for the performance
    of Subtenant's obligations under

                                      -3-

<PAGE>

     this Sublease and under the Master Lease. Sublandlord shall not be required
     to keep this security deposit separate from its general funds and Subtenant
     shall not be entitled to interest thereon. If Subtenant defaults on any
     provision of this Sublease or of the Master Lease beyond the applicable
     cure or grace period, Sublandlord may, without prejudice to any other
     available remedy, apply all or part of the Security Deposit to any rental
     or other sums in default; to any amount Sublandlord may spend or be
     obligated to spend exercising or protecting its rights  under the Sublease
     or the Master Lease; or to any reasonable expense, loss or damage
     Sublandlord may suffer because of Subtenant's default. In the event
     Sublandlord is required to apply any portion of the Security Deposit,
     Subtenant shall, within five (5) days following written notice thereof from
     Sublandlord, replenish the Security Deposit by the amount so applied by
     Sublandlord. The Security Deposit (less any amounts necessary to cure any
     then existing defaults or to make any necessary repairs) shall be returned
     to Subtenant within thirty (30) days after the expiration or other
     termination of the Sublease.

 9.  Use. Subtenant shall at all times use the Premises in accordance with the
     terms of the Master Lease and all applicable laws, rules, codes,
     regulations and ordinances.

10.  Condition of Premises/Early Occupancy. Subtenant agrees to accept the
     Premises in "as is" condition, and agrees that Sublandlord shall not be
     obligated to perform or be responsible for any construction, alteration,
     maintenance or repair with respect to all or any portion of the Premises.
     Notwithstanding the foregoing Sublandlord agrees that (i) the custom
     fitted reception desk existing in the Premises, shall remain therein for
     Subtenant's use, and (ii) Sublandlord shall duly and timely repair and
     restore in a good workmanlike manner, all areas disturbed by Sublandlord's
     removal of any fixtures or improvements prior to Subtenant's occupancy of
     the Premises. Provided that Master Landlord has consented to this Sublease
     in writing and Subtenant has paid the Security Deposit required in Section
     3(m), Subtenant shall be permitted access to the Premises on or before
     March 15, 2001 for the purposes of preparing the Premises for its use and
     occupancy and making the Subtenant Improvements (as defined in Section 11
     (c)), provided that all provisions of this Sublease (except the provisions
     relating to the payment of any Base Rent or additional rent) shall apply
     during any such early occupancy period.

11.  Maintenance and Repairs.

          a.  Maintenance. During the Term hereof and at Subtenant's sole cost
              and expense, Subtenant shall keep and maintain the Premises and
              any fixtures, facilities and equipment contained thereon, in good
              condition and repair and otherwise in compliance with this
              Sublease, the Master Lease and all applicable laws, ordinances,
              codes, rules and regulations, and in conformity with the rules and
              regulations of underwriters' fire prevention agencies ordinary
              wear and tear and damage due to casualty or condemnation
              excepted.

          b.  Repairs and Reconstruction. Subtenant shall promptly and at its
              sole cost and expense repair any damage or destruction to the
              Premises which occurs

                                      -4-
<PAGE>

          during the term of this Sublease and is directly caused by Subtenant
          or Subtenant's employees, agents, contractors or business invitees
          which are not required to be made by Master Landlord under the Master
          Lease. The repairs shall be completed in a good and workmanlike manner
          in accordance to all applicable laws, ordinances, codes, rules and
          regulations or the governing political agency.

       c. Alterations or Improvements. Sublandlord agrees that Subtenant may
          make and construct all improvements to the Premises described in
          Exhibit C attached hereto (the "Subtenant Improvements"). Except for
          the Subtenant Improvements, Subtenant shall not make, or permit to be
          made, any alterations or additions to any electrical, plumbing,
          heating or cooling systems, nor shall Subtenant make any interior
          alterations or improvements in the Premises without the prior written
          consent of Sublandlord which shall not be unreasonably withheld, and
          without complying with all requirements of the Master Lease, including
          that of approval by the Master Landlord. Subtenant shall promptly pay
          all costs, expenses and charges thereof, shall make such alterations
          and improvements in accordance with applicable laws and building codes
          and in a good and workmanlike manner, and shall fully and completely
          indemnify and defend (with counsel reasonably acceptable to
          Sublandlord and Master Landlord) Sublandlord and Master Landlord, as
          the case may be, from and against any mechanic's lien or other liens
          or claims in connection with the making of such alterations and/or
          improvements of a structural nature to the Premises. Subtenant shall
          promptly repair any damage to the Premises, or to the Building caused
          by any alterations, additions or improvements of the Premises by
          Subtenant.

       d. Sublandlord's Inspection Rights. Upon reasonable prior notice and
          without interfering with Subtenant's daily business operations,
          Sublandlord shall have the right to inspect the Premises, accompanied
          by a representative of the Subtenant, to assure Subtenant's
          compliance with the use provisions and maintenance, repair and
          reconstruction obligations of Subtenant under this Sublease, the
          Master lease and all applicable laws, ordinances, codes, rules and
          regulations.

12.  Rights and Remedies. Nothwithstanding anything to the contrary contained in
     the Master Lease, in the event Subtenant defaults in the performance of its
     obligations under this Sublease, including but not limited to the payment
     of all rentals and other amounts provided herein, Sublandlord shall be
     entitled, within seven (7) days following receipt by Subtenant of notice
     thereof as to monetary defaults, and within seven (7) days of receipt by
     Subtenant of written or other notice with respect to any failure of
     performance of the other terms, conditions or covenants of this Sublease
     to be observed or performed by Subtenant, to exercise any and all of the
     rights and remedies available under this Sublease, at law or in equity,
     including, without limitation, the same rights and remedies against
     Subtenant as Master Landlord would have against Sublandlord in the event of
     default under the terms of the Master Lease. Any amount due from Subtenant
     to Sublandlord which is not paid when due shall

                                      -5-


<PAGE>

     bear interest at ten percent (10%) per annum until paid, but the payment of
     such interest shall not excuse nor cure the default.

13.  Sublandlord's Right to Cure Defaults. At any time during the Term upon
     notice in writing to Subtenant, Sublandlord may, but is not obligated to,
     cure or otherwise discharge any default beyond any application cure period
     by Subtenant under this Sublease. Any and all costs or expenses which
     Sublandlord may expend or incur for this purpose, including but not limited
     to the payment of rent under the Master Lease, shall be due and payable in
     full promptly upon Sublandlord's written demand thereof. All costs and
     expenses incurred by Sublandlord under this paragraph shall bear interest
     at a rate of ten percent (10%) per annum for the time period commencing on
     the date Sublandlord incurs such cost or expense and ending on (and
     including) the date Subtenant reimburses Sublandlord therefor.

14.  Performance. Subject to the prior written consent of Master Landlord,
     Sublandlord may direct Subtenant to perform directly to Master Landlord
     such obligations of Subtenant under this Sublease as Sublandlord shall
     designate, and such performance shall be applied in reduction of
     Subtenant's obligations under this Sublease.

15.  No Waiver. No waiver of any breach or violation of any of the covenants,
     agreements and obligations of Subtenant by Sublandlord under this Sublease
     shall be construed, taken or held to be a waiver of any other breach or
     violation or a waiver, acquiescence in or consent to any further or
     succeeding breach or violation of the same covenant, agreement or
     obligation.

16.  Indemnification. In addition to the waiver and indemnification provisions
     contained in the Master Lease and to the extent not due to the negligence
     or willful misconduct of Sublandlord, its employees, contractors, invitees
     or customers, Subtenant hereby waives all claims which it may have against
     Sublandlord, and Subtenant indemnifies and agrees to defend (with counsel
     acceptable to Sublandlord or its successors and assigns) and to hold
     Sublandlord and its successors and assigns harmless for, from and against
     any and all claims, damages or liabilities, including reasonable attorneys'
     fees and expenses, imposed upon, incurred by or asserted against
     Sublandlord or its successors and assigns which arise solely out of any
     violations by Subtenant of this Sublease or which may arise out of or are
     in any manner connected with Subtenant's use and occupancy of the Premises.

     Unless due to the negligence or willful misconduct of Subtenant, its
     agents, employees, or invitees, Sublandlord hereby indemnifies and agrees
     to defend (with counsel acceptable to Subtenant or its successors and
     assigns) and to hold Subtenant and its successors and assigns harmless for,
     from and against any and all claims, damages, or liabilities, including
     reasonable attorney's fees and expenses, imposed upon, incurred by or
     asserted against Subtenant or its successors and assigns which arise out of
     any violations by Sublandlord of this Sublease or of the Master Lease or
     which may arise out of or are in any manner connected with Sublandlord's
     use and occupancy of the "Leased Premises" demised to it pursuant to the
     Master Lease.

                                     - 6 -


<PAGE>

17. Insurance. Without limiting Subtenant's obligations to procure and maintain
    insurance satisfying the requirements of the Master Lease, all such
    insurance maintained by Subtenant with respect to the Premises during the
    Term of this Sublease shall name both Sublandlord and Master Landlord as
    additional insureds, as their respective interests may appear.

18. Subordination. This Sublease is subject and subordinate to all of the
    provisions of the Master Lease, and Subtenant shall not permit any act or
    omission that will violate any of the provisions of the Master Lease, or
    which could or would cause Sublandlord or Subtenant to be in violation
    thereof.

19. Termination of Master Lease. In the event of any termination of the Master
    Lease, this Sublease shall terminate and the parties shall be relieved from
    all further liabilities and obligations hereunder; provided, however, if
    this Sublease terminates as a result of any default of Subtenant under this
    Sublease or the Master Lease, or both, Subtenant shall be liable to
    Sublandlord for all damage actual and direct suffered by Sublandlord as a
    result of such termination and if this Sublease terminates as a result of
    any default of Sublandlord under this Sublease or Master Lease, or both,
    Sublandlord shall be liable to Subtenant for all damage actual and direct
    suffered by Subtenant as a result of such termination.

20. Holdover by Subtenant. In the event Subtenant remains in possession of the
    Premises or fails to remove its property from the Premises after the
    expiration of the Term or the earlier termination of this Sublease for any
    reason without executing a new agreement under which it may lawfully use and
    occupy the same, Subtenant shall fully and timely pay to Sublandlord such
    sums as the Master Lease requires the "Tenant" to pay. Notwithstanding
    anything to the contrary contained herein, the holding over by Subtenant
    shall create in Subtenant no right of occupancy of the Premises, without the
    prior written consent of Sublandlord and Master Landlord. Unless Sublandlord
    and Subtenant agree to the contrary in writing, Subtenant's occupancy of the
    Premises after the expiration of the Term or after the termination of this
    Sublease shall create a tenancy at Sufferance.

21. Removal Of Subtenant's Property. Notwithstanding anything to the contrary in
    the Master Lease, Subtenant shall, at Subtenant's sole cost and expense,
    remove all personal property including, but not limited to, equipment,
    furniture, fixtures and all other personal property of Subtenant on the
    Premises prior to the expiration or sooner termination of this Sublease or
    the Master Lease.

22. Transfer. Notwithstanding anything contained in the Master Lease, Subtenant
    shall not sell, transfer, convey, mortgage, sublet, quitclaim, pledge,
    assign, permit or suffer the use or occupancy of the Premises or any part
    thereof by anyone other than Subtenant or otherwise grant any party any
    interest in this Sublease or the Premises, in whole or in part, without
    Sublandlord's prior written consent which will not be unreasonably withheld,
    and the prior written consent of Master Landlord as set forth in the Master
    Lease. This Sublease and Subtenant's interest hereunder shall not be
    assignable by operation of law. Any attempted or actual transfer by
    Subtenant

                                      -7-
<PAGE>

    (whether by way of an assignment, sublease or otherwise) without
    Sublandlord's prior written consent shall be null and void and of no force
    or effect, shall convey no right or interest hereunder to the purported
    transferee.  Any approved transfer of Subtenant's interest hereunder shall
    comply with all requirements of the Master Lease and Subtenant shall be
    responsible for the payment of all costs, fees and expenses incurred by
    Sublandlord related to such transfer not to exceed $2,500.00.

23. Quiet Enjoyment.  Sublandlord has received no notice of any default under
    the Master Lease, and to its actual knowledge without investigation,
    Sublandlord is not aware of any default by Sublandlord under the Master
    Lease.  Sublandlord represents that the Master Lease attached hereto is in
    full force and effect and has not been modified or amended and that Master
    Landlord is not in default under the Master Lease.  Provided that Subtenant
    performs all of its duties and obligations under this Sublease and observes
    all of the terms and conditions of the Master Lease as they relate to the
    Premises sublet hereunder, Sublandlord shall not take any actions to
    disturb Subtenant's quiet enjoyment of the Premises.

24. Notices.  All notices, demands and communications of any kind which either
    party to this Sublease may desire or be required to serve upon the other
    shall be in writing and served to the parties at the addresses set forth
    in Section 3 above.  All such notices shall be served by documented
    personal service and shall be effective upon documented delivery or
    documented refusal to accept such delivery at the above-mentioned address,
    whereupon such service shall be deemed complete, or by depositing a copy
    thereof with the United States mail by certified or registered mail,
    postage prepaid with return receipt requested or an express delivery
    service, in which event such service shall be deemed complete on receipt by
    the addressee or documented failure to accept delivery or pick up the
    notice at the Post Office.  Either party may change its address from time
    to time by notice given in accordance herewith.

25. Authority.  Sublandlord and Subtenant represent and warrant that the
    individuals executing this Sublease are duly authorized by the entity on
    whose behalf they are signing, and that this Sublease is binding upon such
    entity.

26. Professional Fees and Costs.  In the event of any legal action or proceeding
    brought by either party hereto against the other arising out of this
    Sublease, the prevailing party shall be entitled to recover its reasonable
    attorneys' fees incurred in such legal action or proceeding, together with
    all costs of such action or proceeding.  In the event Sublandlord is
    required to use a collection agency, an attorney, or any other consultant
    in order to enforce the obligations of Subtenant under this Sublease, all
    such costs and expenses of Sublandlord shall be considered to be additional
    rent due under this Sublease and shall be due and payable within five (5)
    days of receipt of Sublandlord's documented invoice therefor and subject to
    interest at the rate set forth in Section 13 above if not timely paid.

                                      -8-

<PAGE>

     27.  Sublandlord's Consent.  Whenever Sublandlord's consent is required
          under this Sublease, it shall be reasonable for Sublandlord to
          condition its consent on the approval of the Master Landlord.

     28.  Notices Under Master Leases.  Within two (2) days after receipt
          thereof, Sublandlord shall deliver to Subtenant any and all notices
          that Sublandlord receives from Master Landlord under the Master Lease.

     29.  Master Landlord's Consent.  This Sublease is subject to and
          conditioned upon the written consent of Master Landlord, and the
          parties shall have no rights hereunder until the "Consent of Master
          Landlord" section of this Sublease is executed by Master Landlord.  If
          Sublandlord is required to pay any fees to Master Landlord in
          connection with securing this consent, Subtenant shall reimburse
          Sublandlord for same upon consent to the Sublease by Master Landlord,
          in an amount not to exceed $150.  In the event Sublandlord has not
          obtained Master Landlord's consent to the Sublease in the form
          attached hereto on or before March 15, 2001, then Subtenant may
          terminate this Sublease by delivering written notice thereof to
          Sublandlord.

IN WITNESS WHEREOF, Sublandlord and Subtenant have executed this Sublease as of
the date first set forth above.

SUBLANDLORD:                                SUBTENANT:

INTEGRATED INFORMATION                      iTRACS Corporation, a Delaware
SYSTEMS, INC., a Delaware corporation       corporation


By: /s/ Jeffrey Frankel                     By: /s/ John A. Reedy
    ------------------------------              --------------------------------

Its:  VP                                    Its: V.P. Finance & Administration
    ------------------------------               -------------------------------

                                      -9-
<PAGE>

                          CONSENT OF MASTER LANDLORD

          Master Landlord hereby consents to the foregoing Sublease and Addendum
to Sublease without waiver of the restriction concerning further subletting.
Further, Master Landlord agrees and acknowledges as follows:

     1.   The Master Lease is in full force and effect and has not been modified
          or amended.  The Tenant under the Master Lease and Sublandlord under
          this Sublease is not in default under the Master Lease and Master
          Landlord knows of no defaults by Master Landlord under the Master
          Lease.

     2.   In consenting to this Sublease, Master Landlord agrees and
          acknowledges that the use of the Premises shall be for the purpose of
          business and sales offices of iTRACS Corporation.

     3.   Master Landlord agrees to simultaneously deliver any notices to the
          Tenant under the Master Lease and to Subtenant at the address
          specified herein.

     4.   Master Landlord agrees that Subtenant may make the Subtenant
          Improvements described in Section 11(c) of the Sublease and Exhibit A
          of the Addendum to Sublease, all without any further or additional
          approval requirements of Master Landlord (except as expressly set
          forth therein).

     5.   Master Landlord agrees to allow Subtenant to examine the Master
          Landlord's books and records as provided in Paragraph 43 of the
          Addendum to the Master Lease.

     6.   Notwithstanding anything in the Master Lease or the Rules and
          Regulations to the Contrary, Master Landlord agrees to enforce all
          rules and regulation uniformly amongst all tenants.



                                       MASTER LANDLORD:

                                       Birtcher Arizona, L.L.C., manager for

                                       AMBERJACK, LTD.



                                       By:  /s/ Theodore Raban
                                          --------------------------------------
                                       Its:   President
                                           -------------------------------------
<PAGE>

                             ADDENDUM TO SUBLEASE
                             --------------------

     THIS ADDENDUM TO SUBLEASE (this "Addendum") is entered into this 5th day of
March, 2001, by and between Integrated Information Systems, Inc., a Delaware
corporation ("Sublandlord"), and iTRACS Corporation, a Delaware corporation
("Subtenant").

                                   RECITALS

     A.  On February 27, 2001, Sublandlord and Subtenant entered into that
certain iTRACS Sublease (the "Sublease"), pursuant to which Sublandlord agreed
to lease to Subtenant and Subtenant agreed to lease from Sublandlord the
Premises (as defined in the Sublease).

     B.  Sublandlord and Subtenant now desire to amend the Sublease as set forth
herein. All capitalized terms used herein but not defined herein, shall have the
meaning ascribed to such term in the Sublease.

     NOW, THEREFORE, in consideration of the Premises and other valuable
consideration, the receipt and sufficiency of which is hereby acknowledged by
the parties to this Addendum, the parties do hereby covenant and agree as
follows:

     1.  Sublandlord and Subtenant agree that Section 2 of the Sublease is
deleted in its entirety and replaced with the following:

     "2.  PROVISIONS REGARDING SUBLEASE. This Sublease and all the rights of
parties hereunder are subject and subordinate to the Master Lease. Each party
agrees that it will not, by its act or omission to act, cause a default under
the Master Lease. In furtherance of the foregoing, the parties hereby confirm,
each to the other, that it is not practical in this Sublease to enumerate all of
the rights and obligations of the various parties under the Master Lease and
specifically to allocate those rights and obligations in this Sublease.
Accordingly, in order to afford to Subtenant the benefits of this Sublease and
of those provisions of the Master Lease which by their nature are intended to
benefit the party in possession of the Premises, and in order to protect
Sublandlord against a default by Subtenant which might cause a default or event
of default by Sublandlord under the Master Lease:

     A.  Except as otherwise expressly provided herein, Sublandlord shall
         perform its covenants and obligations under the Master Lease which do
         not require for their performance possession of the Premises and which
         are not otherwise to be performed hereunder by Subtenant on behalf of
         Sublandlord. For example, Sublandlord shall at all times keep in full
         force and effect all insurance required of Sublandlord as tenant under
         the Master Lease.

     B.  Except as otherwise expressly provided herein, Subtenant shall perform
         all affirmative covenants and shall refrain from performing any act
         which is prohibited by the negative covenants of the Master Lease,
         where the obligation to perform or refrain from performing is by its
         nature imposed upon the party in possession of the Premises. If
         practicable, Subtenant shall perform affirmative covenants which are
         also covenants of Sublandlord under the Master Lease at least two (2)
         days prior to the date when Sublandlord's performance is required under
         the Master Lease.

     C.  Sublandlord shall not agree to an amendment to the Master Lease which
         might have an adverse effect on Subtenant's occupancy of the Premises
         or its use of the Premises for their intended purpose, unless
         Sublandlord shall first obtain Subtenant's prior written approval
         thereof.

     D.  Sublandlord hereby grants to Subtenant the right to receive all of the
         services and benefits with respect to the Premises which are to be
         provided by Master Landlord under the Master Lease. Sublandlord shall
         have no duty to perform any obligations of Master Landlord which are,
         by their nature, the obligation of an owner or manager of real
         property. For example, Sublandlord shall not be required to provide the
         services or repairs which the Master Landlord is required to provide
         under the Master Lease. Sublandlord shall have no responsibility for or
         be liable to Subtenant for any default, failure or delay on the part of
         Master Landlord in the performance or observance by Master Landlord of
         any of its obligations under the Master Lease, nor shall such default
         by Master


<PAGE>

           Landlord affect this Sublease or waive or defer the performance of
           any of Subtenant's obligations hereunder except to the extent that
           such default by Master Landlord excuses performance by Sublandlord,
           under the Master Lease. Notwithstanding the foregoing, the parties
           contemplate that Master landlord shall, in fact, perform its
           obligations under the Master Lease and in the event of any default or
           failure of such performance by Master Landlord, Sublandlord agrees
           that it will, upon notice from Subtenant, make demand upon Master
           Landlord to perform its obligations under the Master Lease and,
           provided that Subtenant specifically agrees to pay all costs and
           expenses of Sublandlord and provides Sublandlord with security
           reasonably satisfactory to Sublandlord to pay such costs and
           expenses, Sublandlord will take appropriate legal action to enforce
           the Master Lease."

           2.  Sublandlord and Subtenant agree that Section 18 of the Sublease
is deleted in its entirety without replacement.

           3.  Sublandlord and Subtenant agree that Exhibit C to the Sublease is
                                                    ---------
deleted in its entirety and replaced with Exhibit A attached hereto.
                                          ---------

           4.  Except as and to the extent amended by this Addendum, the
Sublease and all of the terms, conditions and provisions thereof shall, in all
respects, remain unmodified and unchanged and are hereby reaffirmed, ratified
and confirmed and shall remain in full force and effect.

           5.  In the event of any conflict or inconsistency between the
provisions of the Sublease and the provisions of this Addendum, the provisions
of this Addendum shall control.

           6.  This Addendum shall be binding upon and shall inure to the
benefit of the parties hereto and their respective beneficiaries, successors and
assigns.

           7.  This Addendum may be executed in counterparts, each of which
shall be deemed an original and all of which taken together shall constitute one
and the same instrument.

                                      -2-
<PAGE>

     IN WITNESS WHEREOF, Sublandlord and Subtenant have executed this Addendum
as of the date first above written,


                               SUBLANDLORD:

                                    INTEGRATED INFORMATION SYSTEMS, INC.,
                                    a Delaware corporation


                                    By: /s/ DAVID A. WIRTHLIN
                                       --------------------------------

                                   Its: CFO
                                       --------------------------------

                               SUBTENANT:

                                    iTRACS Corporation, a Delaware corporation

                                    By: /s/ JOHN A. REEDY
                                       --------------------------------

                                   Its: V.P. Finance and Administration
                                       --------------------------------

                                      -3-

<PAGE>

                                   EXHIBIT A
                                   ---------


                        Approved Subtenant Improvements


The Master Landlord and Sublandlord, as part of the Sublease Agreement, hereby
agree to the following Subtenant Improvements:

Patching of cracks, holes and other defects in walls

Painting of entire leased space

Subject to the approval of the Master Landlord (which approval shall not be
unreasonably withheld), placement of iTRACS Corporation name on front entry
doors

Placement of iTRACS name and logo on wall behind reception desk

Subject to the approval of the Master Landlord (which approval shall not be
unreasonably withheld), placement of Suite number on front entry doors

Placement of furniture in front reception area

Placement of lighting (spot lights), and Access Camera in reception area

Placement of furniture and white boards in all of the offices, training room,
conference rooms and cubicles

Placement of names on offices

Replacement of warn patches of carpet

Cleaning of carpet throughout leased space

Building out of a storage facility with modular furniture

Reconfiguring of the Sublandlord Telecommunications closet and wiring for the
leased facility to satisfy Subtenant's telecommunications, data, facsimile and
computing requirements

Replacement of projector, speakers and screen for training room that Sublandlord
is taking from existing facility

Placement of coffee service in kitchen and outside romper room along with water
and possibly soda service

Placement of scalers on front entry way

Replace passage sets with lock sets on office doors

Placement of electrical outlets (220 Volts) in server room

Removal of name decals on offices

Removal of window treatment on demo room

Removal of "Romper Room" door lettering

Addition of whiteboards in offices, conference rooms, training rooms and
cubicles

                                      -4-