**Exhibit 10.21**

**FIFTHAMENDMENT TO OFFICE BUILDING LEASE AGREEMENT**

ThisFifth Amendment to Office Building Lease Agreement (this “**Amendment**”) is made and entered intothis 18th day of April, 2007, by and between WESTCOREPYRAMID, L.P., a Delaware limited partnership (the “**Landlord**”), and EVOLVING SYSTEMS, INC.,a Delaware corporation (the “**Tenant**”).

**RECITALS**

A.                                   MeridianAssociates West, a Colorado general partnership, the predecessor-in-interest toPacifica Holding Company, a Colorado corporation, the predecessor-in-interestto Mack-Cali Realty, L.P., a Delaware limited partnership, thepredecessor-in-interest to Landlord, and Tenant entered into that certainOffice Building Lease Agreement dated March 30, 1995, as amended by thatcertain Amendment Number One to Lease Agreement dated October 11, 1996 (“**First Amendment**”), that certainAmendment Number Two to Lease Agreement dated October 22, 1999 (“**Second Amendment**”), that certain ThirdAmendment to Office Building Lease Agreement dated July 17, 2002 (“**Third Amendment**”), and that certainFourth Amendment to Office Building Lease Agreement dated May 24, 2004 (“**Fourth Amendment**”) (the Office BuildingLease Agreement, the First Amendment, Second Amendment, Third Amendment andFourth Amendment are hereinafter sometimes collectively referred to as the “**Original Lease**”), with respect tocertain premises located within the office building (the “**Building**”**)** located at 9777 Pyramid Court, Englewood, Colorado, as moreparticularly described therein.

B.                                     The term of theOriginal Lease is currently set to expire on May 31, 2007.  Tenant has requested, and Landlord hasaccepted, an extension of the term of the Original Lease.

C.                                     Landlord andTenant desire (i) to extend the term of the Original Lease, (ii) to reduce thesize of the existing premises, (iii) to establish the Base Rent and BaseOperating Expenses for the extension term, and (iv) to provide other amendmentsto the Original Lease, all subject and pursuant to the terms and conditions setforth below.

**AGREEMENT**

NOW THEREFORE, in consideration of the premises andthe mutual covenants hereinafter set forth, the parties agree as follows:

1.                                       New PremisesLease Term.  The NewPremises Lease Term shall be extended for an additional term of sixty-five (65)months commencing on June 1, 2007 (the “**ExtensionDate**”) and terminating on October 31, 2012 (the “**Termination Date**”).

2.                                       New Premises.  Commencing on the Extension Date, the NewPremises shall be deemed to contain approximately twenty-four thousand threehundred five (24,305) rentable square feet of space located on the first floorof the Building as depicted on the floor plan attached hereto as **Exhibit A**.

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3.                                       Monthly BaseRent.  Effective on the ExtensionDate, Section 4 of the Lease is amended by deleting it in its entirety andinserting the following in lieu thereof:

Tenant shall pay to Landlord as Base Rent for theNew Premises, accruing on and after the Extension Date and monthly thereafterin accordance with the terms of the Original Lease, as follows:
| **Period**                                | ** ** | **Rent/Sq.Ft.** | ** ** | **Annual Rent** | ** ** | **Monthly Rent** | ** ** |
|-------------------------------------------|------------|-----------------|------------|----------------------|------------|-----------------------|------------|
| Extension Date – October 31, 2007    |       | $               | 0.00       |                 | $          | 0.00                  |       | $ | 0.00 |   |
| November 1, 2007 – October 31, 2008  |       | $               | 19.25      |                 | $          | 467,871.25            |       | $ | 38,989.27 |   |
| November 1, 2008 – October 31, 2009  |       | $               | 19.75      |                 | $          | 480,023.75            |       | $ | 40,001.98 |   |
| November 1, 2009 – October 31, 2010  |       | $               | 20.25      |                 | $          | 492,176.25            |       | $ | 41,014.69 |   |
| November 1, 2010 – October 31, 2011  |       | $               | 20.75      |                 | $          | 504,328.75            |       | $ | 42,027.40 |   |
| November 1, 2011  – Termination Date |       | $               | 21.25      |                 | $          | 516,481.25            |       | $ | 43,040.10 |   |

 

Tenant’s Pro Rata Share of Increased OperatingExpenses as provided herein and such other charges as are required by the termsof this Lease to be paid by Tenant shall be referred to as “**Additional Rent**.”  Landlord shall have the same rights as to theAdditional Rent as it has in the payment of Base Rent.  The Base Rent, Additional Rent and all otheramounts due to be paid under this Lease may be referred to herein collectivelyas “**Rent**.”

The term “**LeaseYear**” as used herein shall be each twelve (12) month period inthe New Premises Lease Term commencing on June 1 of each calendar year duringthe New Premises Lease Term.

4.                                       Base YearOperating Expenses.

(a)                                  “**Base Operating Expenses**” shall mean anamount equal to the actual Operating Expenses for the Building Complex for thecalendar year 2007.

(b)                                 Effective as ofthe Extension Date, Subparagraph 5.B. of the Third Amendment is hereby deletedand restated in its entirety as follows:

5.B.    From and after the ExtensionDate, Tenant shall pay to Landlord Tenant’s Prorata Share of any increases inOperating Expenses in excess of Base Operating Expenses (the “**Increased Operating Expenses**”) duringeach calendar year of the New Premises Lease Term and any extensionthereof.  All amounts required to be paidby Tenant shall be paid within thirty (30) days following billing therefor byLandlord.  Beginning on January 1, 2008,and continuing each month thereafter during the New Premises Lease Term, or anyextension thereof, Tenant shall pay to Landlord, at the same time as the BaseRent is paid, an amount equal to one-twelfth (1/12) of Landlord’s estimate (asdetermined by Landlord’s Accountants) of Tenant’s Prorata Share of theIncreased Operating 

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Expenses for theparticular calendar year, with a final adjustment to be made between theparties at a later date for said calendar year.

(1)                                  Assoon as practicable following the end of each calendar year during the NewPremises Lease Term, or any extension thereof, Landlord shall submit to Tenanta statement prepared by a representative of Landlord setting forth the exactamount of Tenant’s Prorata Share of the Increased Operating Expenses for thecalendar year just completed.  Beginningwith said statement for the second full calendar year, it shall also set forththe difference, if any, between Tenant’s actual Prorata Share of the IncreasedOperating Expenses for such calendar year just completed and the estimatedamount of Tenant’s Prorata Share of Increased Operating Expenses.  Each such statement shall also set forth theprojected Increased Operating Expenses, if any, for the new calendar year andthe corresponding increase in Tenant’s Prorata Share of the Increased OperatingExpenses computed in accordance with the foregoing provisions; provided,however, in no event will the Rent to be paid by Tenant hereunder ever be lessthan the Base Rent as it is to be adjusted for such calendar year.  To the extent that Tenant’s Prorata Share ofthe Increased Operating Expenses for the period covered by such statement isdifferent from the estimated amount upon which Tenant paid Rent during thecalendar year just completed, Tenant shall pay to Landlord the difference incash within thirty (30) days following receipt by Tenant of such statement fromLandlord or receive a credit on the next month’s rental owing hereunder, as thecase may be.  Until Tenant receives suchstatement, Tenant’s monthly Rent for the new calendar year shall continue to bepaid at the rate paid for the particular calendar year just completed, butTenant shall commence payment to Landlord of the monthly installments of Renton the basis of such statement beginning on the first day of the monthfollowing the month in which Tenant receives such statement.  Moreover, Tenant shall pay to Landlord ordeduct from the Rent, as the case may be, on the date required for the first paymentof Rent, as adjusted, the difference, if any, between the monthly installmentsof Rent so adjusted for the new calendar year and the monthly installments ofRent actually paid during the new calendar year.

(2)                                  Inaddition to the above, if, during any particular calendar year, there is achange in the information on which Landlord’s Accountants based the estimateupon which Tenant is then paying its estimated Tenant’s Prorata Share of theIncreased Operating Expenses so that such estimate furnished to Tenant is nolonger accurate, Landlord shall be permitted to revise such estimate bynotifying Tenant and there shall be such adjustments made in the monthlyestimated Tenant’s Prorata Share of the Increased Operating Expenses on thefirst day of the month following the serving of such statement on Tenant asshall be necessary by either increasing or decreasing, as the case may be, theamount of Tenant’s Prorata Share of the Increased Operating Expenses then beingpaid by Tenant for the balance of the calendar year, as well as an appropriateadjustment in cash based upon the amount theretofore paid by Tenant during suchparticular calendar year pursuant to the prior estimate.

(3)                                  Inthe event the Rentable Area is not fully occupied during any particular calendaryear, Landlord’s Accountants may adjust those Operating Expenses which areaffected by the occupancy rates for the particular calendar 

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year, or portionthereof, as the case may be, to reflect an occupancy of not less thanninety-five percent (95%) of such Rentable Area.  In the event the Rentable Area is not fullyoccupied during the calendar year 2007, which serves as the basis for thecalculation of Base Operating Expenses, Landlord’s Accountants shall adjustthose Operating Expenses which are affected by the occupancy rates for thecalendar year 2007, or portion thereof, as the case may be, to reflect anoccupancy of not less than ninety-five percent (95%) of such Rentable Area.

(4)                                  Ifthe calendar year is not concurrent with the Lease Year, Landlord shall, at anytime during the New Premises Lease Term, or any extension thereof, make alladjustments provided for in this Paragraph 5 with an appropriate proration forthe Lease Year in which the New Premises Lease Term or any extension begins orends.  In addition, Landlord may elect atany time during the New Premises Lease Term or any extensions thereof to makeall adjustments provided for in this Paragraph 5 on a Fiscal Year basis with anappropriate proration for the calendar year in which such conversion is madeand in which the term ends and all references in this Lease to calendar yearshall thereafter be deemed to refer to “**FiscalYear**”.

(5)                                  Landlord’sand Tenant’s responsibilities with respect to the Operating Expense adjustmentdescribed herein shall survive the expiration or early termination of thisLease.

(c)                                  Commencingas of the Extension Date, Tenant’s Prorata Share shall be deemed to be20.207%.  The terms Tenant’s Porata Shareand Tenant’s Pro Rata Share are used interchangeably in the Original Lease andshall carry the same meaning for all purposes hereof.

(d)                                 Nothingin the foregoing shall be deemed to modify any obligations of Tenant withrespect to Operating Expenses for any period prior to the Extension Date.

5.                                       Tenant FinishWork.  Provisions regarding anyremodeling of or tenant finish work to be completed in the  New Premises shall be as set forthbelow.  Except as provided below,Landlord shall have no obligation for completion or remodeling of the  New Premises and Tenant shall accept thePremises in its ***“as is”***condition on the Extension Date:

(a)                                  TenantImprovement Allowance. Landlord agrees to pay Tenant a tenant improvement allowance of TwoHundred Ninety-One Thousand Six Hundred Sixty and No/100ths U.S. Dollars($291,660.00) (the “**Tenant ImprovementAllowance**”) as contribution toward the cost of tenantimprovement work performed in the New Premises (collectively, the “**Tenant Finish Costs**”**)**. The Tenant Improvement Allowance shall be applied toward (i) the cost oftenant improvement work completed within the rentable area of the New Premisesin

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accordance with the Construction Drawings (asdefined below), excluding, however, any movable furniture, equipment and tradefixtures not physically attached to the Premises (collectively, the “**Tenant Work**”), and (ii) the cost oftenant improvement work completed within the rentable areas of the New Premisesin accordance with Tenant’s IT Work (as defined below), as well as any softcosts, such as architectural, engineering, cabling and wiring costs incurred byTenant in connection with Tenant’s Work or Tenant’s IT Work.  Landlord shall pay the costs of Tenant’s ITWork from the proceeds, if any, of the Tenant Improvement Allowance withinthirty (30) days after receipt of invoices, reasonable supportingdocumentation, and lien waivers in such form as Landlord may reasonablyrequire.  Any unused portion of theTenant Improvement Allowance upon completion of Tenant’s Work and Tenant’s ITWork will not be refunded to Tenant and will not be available to Tenant as acredit against any obligations of Tenant under the Lease.   Landlord shall have the right to charge aconstruction management fee equal to two and one-half percent (2.5%) of theTenant Finish Costs, which amount shall be deducted from the Tenant ImprovementAllowance.

(b)                                 Design of Tenant’s Work.  Landlord and Tenant have approved thosecertain pricing plans for the Premises prepared by Intergroup Architects (the “**Architect**”) attached hereto as **Exhibit C**(collectively, the “**Pricing Plans** “).  No changes may be made to the Pricing Planswithout the written approval of Landlord and Tenant.

(c)                                  Construction Drawings.  Within fifteen (15) business days after thedate of this Amendment, Landlord shall cause the Architect to prepare the constructiondrawings for Tenant’s Work in the New Premises (“**Construction Drawings**”) based upon the Pricing Plans andshall submit the Construction Drawings for Tenant’s approval.  Tenant shall either approve the ConstructionDrawings or submit, in writing, exceptions to the Construction Drawings toLandlord within five (5) business days of Tenant’s receipt of the ConstructionDrawings.  If Tenant does not respond tothe Construction Drawings within such five (5) business day period, Tenantshall be deemed to have approved the Construction Drawings.  If Tenant submits exceptions to theConstruction Drawings, Landlord shall respond to any of Tenant’s exceptionswithin five (5) business days of receipt thereof.  This procedure shall be repeated until bothparties agree upon the final Construction Drawings.  After approval of the Construction Drawingsno further changes may be made without the prior written approval of Landlord.

(d)                                 Construction ofTenant’s Work.  OnceLandlord and Tenant agree on the final Construction Drawings, Landlord shall beresponsible for the execution and administration of the construction of Tenant’sWork, which shall be done in accordance with the following provisions:

(i)                                     ContractorSelection.  Within fifteen (15)business days after the date Landlord and Tenant agree upon the finalConstruction Drawings, Tenant’s Work shall be competitively bid to three (3)general contractors, and Tenant shall be provided a reasonable opportunity toprovide input into the bid and bid review process.  Landlord shall select a contractor for Tenant’sWork, subject to Tenant’s reasonable approval, which approval shall not beunreasonably withheld.  The selectedcontractor or subcontractor may be referred to herein as the “**Contractor**”.  The contract for the Tenant’s Work shall bebetween Landlord and the Contractor.

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(ii)                                  Permitting.  Landlord or the Contractor shall submit theConstruction Drawings to the proper authorities for a building permit.  Landlord will cause Landlord’s Architect tomake any changes to the Construction Drawings which are requested by theapplicable governmental authorities to obtain the building permit.  Any such changes shall be subject to Tenant’spayment of any excess costs as described below.

(iii)                               Coordinationwith Tenant’s IT Work.  In connectionwith the Tenant’s Work, Tenant will be entering into contracts for theperformance of electrical, wiring and other services related to the relocationof Tenant’s computer rooms and telecommunications services within the NewPremises (collectively, “**Tenant’s IT Work**”).  Landlord acknowledges that because Tenantwill be occupying the New Premises during the construction of Tenant’s Work andbecause Tenant will also be contracting for the construction of Tenant’s ITWork, Landlord’s Contractor will need to closely coordinate with Tenant andTenant’s contractor on the schedules for performance of Tenant’s Work with theperformance of Tenant’s IT Work.  Forexample, some of Tenant’s Work must be sequenced such that computer serversused by Tenant for its ongoing business must be moved from the computer roomswithin the 1A wing of the New Premises before any demolition or remodeling ofsuch computer rooms can be performed.

(iv)                              TenantImprovement Allowance Over Runs. Landlord shall pay the Tenant Finish Costs in the amount up to theTenant Improvement Allowance, less any deductions for Landlord’s constructionmanagement fee as noted above.  IfLandlord estimates that the Tenant Finish Costs will exceed the TenantImprovement Allowance, the projected excess shall be paid by Tenant upondemand.  Landlord shall be under noobligation to commence or continue performing Tenant’s Work until Tenant hasmade such payment.

(e)                                  Costsfor Moving Telecommunications “Point of Presence” for Other Building Tenants.  Currently, one or more telecommunicationscompanies have a “point of presence” or “POP” in Tenant’s large computer roomlocated on the 1C wing of the New Premises. These telecommunications POPs are used to provide services to othertenants in the Building.  Because suchspace will no longer be used as a computer room after Tenant’s Work has beencompleted, such telecommunications POP(s) need to be moved.  The costs of moving such telecommunicationsPOP(s) are not the responsibility of the Tenant and shall not be included incosts charged against the Tenant Improvement Allowance.  Landlord shall be responsible for notifyingthe telecommunications carriers of the need to move their POPs and Tenant willreasonably cooperate with Landlord to effect the movement of such POPs from the1C wing computer room.

(f)                                    SwingSpace.  Upon Tenant’s writtenrequest, Landlord will permit Tenant to occupy Suite 200 “C” of the Building(the “**Swing Space**”) for noadditional rent until such time as Landlord notifies Tenant that the NewPremises are ready for occupancy.  Duringsuch occupancy, the Swing Space shall be deemed part of the New Premises andshall be subject to all terms of the Lease, other than payment of Base Rent,Operating Expenses or the Tenant Improvement Allowance.  Tenant shall have two (2) weeks to vacate theSwing Space after receiving notice from Landlord that the New Premises areready for occupancy.

(g)                                 Decommissioningof Cooling Tower Unit.  Landlordacknowledges and agrees that in connection with Tenant’s IT Work, Tenant willbe terminating the use of the Cooling Tower Unit that it is currently using foradditional cooling for its computer rooms. Within the earlier to occur of: (a) six (6) months after Tenant is nolonger using the Cooling 

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Tower Unit; and(b) two hundred forty (240) days after the date of this Amendment, Tenant shallcause the Cooling Tower Unit to be removed from the Building in compliance withall applicable laws.  Prior to commencingthe removal of the Cooling Tower Unit, Tenant shall submit all plans andspecifications therefore for Landlord’s reasonable review and approval.  Tenant shall promptly repair any damage tothe roof resulting from such removal.  AtLandlord’s election, Tenant shall coordinate such removal with Landlord’sroofing contractor.

(h)                                 NewCooling Unit Installation.  Landlordacknowledges and agrees that in connection with Tenant’s IT Work, Tenant willrequire the installation of new cooling units to provide additional cooling forits computer rooms, and that installation of such cooling units will involveinstallation of units on the exterior of the Building to vent heat from theinterior units to the outside (collectively, the “Cooling Equipment”).  The location, size, type and manner ofinstallation of the Cooling Equipment shall be subject to Landlord’s priorwritten approval.  Tenant must installand maintain all such Cooling Equipment in accordance with all applicable laws,and shall be responsible, at Tenant’s sole cost and expense, for obtaining anypermits and approvals required from any and all governmental orquasi-governmental agencies having jurisdiction over the Building.  Landlord may require Tenant and/or thecompany providing services to Tenant in connection with any such CoolingEquipment to pay for any costs incurred by Landlord in connection with Tenant’sinstallation, operation and maintenance of the Cooling Equipment.  If any of the Cooling Equipment generatesnoise likely, in Landlord’s reasonable judgment, to disturb other tenants oroccupants of the Building, or if required by any governmental authority, Tenantshall install sound attenuated acoustic enclosures reasonably satisfactory toLandlord designed to eliminate such noise or reduce such noise to acceptablelevels, and/or to screen the Cooling Equipment from view.  All of the provisions of the Lease shallapply to the installation, use and maintenance of the Cooling Equipment,including all provisions relating to compliance with legal requirements,insurance, indemnity, repairs and maintenance. Tenant shall (i) be solely responsible for any damage caused as a resultof the use of the Cooling Equipment by Tenant, its employees, agents, orinvitees, (ii) promptly pay any tax, license, permit or other fees or chargesimposed pursuant to any legal requirements relating to the installation,maintenance or use of Cooling Equipment, and (iii) promptly and diligentlyperform all necessary repairs or replacements to, or maintenance of, theCooling Equipment.  Upon the expirationof this Lease, Tenant shall remove the Cooling Equipment at Tenant’s sole costand expense, and shall restore any damage to the Building caused by the removalof the Cooling Equipment.  If Tenantfails to remove the Cooling Equipment within a reasonable time, then the CoolingEquipment shall be deemed abandoned, and Landlord may cause the same to beremoved, and the Building to be repaired, at Tenant’s expense, which expenseshall be considered Additional Rent and shall survive the expiration or earliertermination of the Lease.

6.                                       SecurityDeposit.  Paragraph 5 of the Lease isdeleted and replaced with the following:

5.                                       SecurityDeposit.  Within five (5) business daysafter mutual execution of this Fifth Amendment, Tenant shall deliver toLandlord an irrevocable letter of credit, in substantially the form attachedhereto as **Exhibit B** andincorporated herein by reference, or such other form reasonably acceptable toLandlord, issued by a bank acceptable to Landlord, payable in Denver, Colorado,in the amount of One Hundred Thousand U.S. Dollars ($100,000.00) which asrenewed, replaced or reduced as set forth herein shall remain in effect for theentire New Premises Lease Term plus sixty (60) days 

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(the “**Security Deposit**”)as security for the Rent payable hereunder, the return of the New Premises ingood order and condition as required in this Lease, and the performance of theterms, covenants, conditions and agreements of Tenant under this Lease.  Tenant shall not assign or encumber the SecurityDeposit.  If the letter of credit is forless than the entire New Premises Lease Term, then for as long as Tenant isrequired to maintain the Security Deposit under this Lease, Tenant shalldeliver to Landlord a renewal or replacement letter of credit which conforms tothe requirements of this Paragraph 5 at least thirty (30) days prior to thedate each letter of credit is to expire, and if either (a) Tenant fails so todeliver the renewal or replacement letter of credit, or (b) if the bank whichissued the letter of credit or Tenant notifies Landlord prior to the expirationdate of any such letter of credit (and each letter of credit other than thefirst letter of credit shall require the bank to do so or if the bank will notagree to do so, then Tenant shall so notify Landlord) that it does not intendto renew or replace the letter of credit, then unless Landlord has previouslyreceived the required renewal or replacement letter of credit, Landlord maydraw on the letter of credit and hold its proceeds, without interest to Tenant,as the Security Deposit.  The SecurityDeposit shall not be applied by Tenant to the payment of Rent or any otheramount for which it may become liable under this Lease, and such SecurityDeposit or its use shall in no way relieve Tenant from the faithful and punctualperformance of all terms, covenants, conditions and agreements herein imposedupon it or cure any default.  If Landlorddraws down on the Security Deposit to satisfy any obligation of the Tenant,Tenant, within ten (10) days after demand, shall deliver to Landlord areplacement or additional letter of credit which satisfies the requirements ofthis Paragraph 5 so that Landlord shall have the full amount of the SecurityDeposit ($100,000.00) at all times during the term of this Lease as existedimmediately prior to such application. Notwithstanding the foregoing, it is agreed that so long as Tenant isnot then in default and demonstrates to Landlord’s reasonable satisfaction thatit has achieved positive Adjusted EBITDA (as defined below) for the immediatelypreceding two (2) fiscal years, then at the end of the twenty-fourth full monthafter the Extension Date, the Security Deposit will be reduced to FiftyThousand U.S. Dollars ($50,000.00).  Forpurposes of this Paragraph 5, the term “Adjusted EBITDA” shall mean Tenant’searnings before interest, taxes, depreciation, amortization, impairment, stockcompensation, gain/loss on foreign exchange transactions and other non-cashexpenses.

Upon delivery of the new Letter of Credit described in this Paragraph 5,Landlord shall release its interest in the existing Letter of Credit that wasprovided to Landlord under the terms of Amendment No. 3 to the Lease.

Landlord agrees that at the termination of this Lease, the SecurityDeposit shall be terminated within sixty (60) days after the New Premises havebeen vacated in good order and condition, provided that Tenant shall havecomplied in all respects with the terms, covenants, conditions and agreementscontained herein.  In the event of asale, lease, assignment or transfer of the New Premises or the Building,Landlord shall have the right to transfer its interest in the Security Depositto its purchaser, assignee, transferee, or any other successor in interest andshall provide in writing the address of such successor, and Landlord shallthereupon be released by the Tenant from all liability for the return of theSecurity Deposit; provided, however, that Landlord shall be responsible forpayment of any administrative fees charged by the issuer of the letter of

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credit in connection with such transfer.  In that event, Tenant agrees to look solelyto the new Landlord as such new Landlord shall have the same responsibilitiesas contained in this Paragraph.  Nothingin this Paragraph 5 shall be construed as limiting Tenant’s liability underthis Lease to the amount of the Security Deposit.

7.                                       Renewal Option.  As additional consideration for the covenantsof Tenant hereunder, Landlord hereby grants to Tenant an option (the “**Option**”) to extend the New PremisesLease Term for an additional term of five (5) years (the “**Option Term**”).  The Option shall supersede any renewaloptions contained in the Original Lease. The Option shall apply only to the original space leased hereunder andshall be on the following terms and conditions:

(a)                                  Writtennotice of Tenant’s interest in exercising the Option shall be given to Landlordno earlier than twelve (12) months and no later than nine (9) months prior tothe expiration of the New Premises Lease Term. If Tenant timely exercises the Option, the Lease shall be deemedextended and thereafter the parties shall execute an amendment to the Leasesetting forth the terms of the extension.

(b)                                 TheOption granted hereunder shall be upon the terms and conditions contained inthe Lease except that monthly fixed rent shall be the fixed rent which Landlordwould quote to third parties for space comparable to the New Premises if itwere to become available for leasing for a lease term scheduled to commence atthe time of the commencement of the Option Term (the “**Market Rate”)**.  The Market Rate may include escalations andpass-throughs.  Notwithstanding anythingto the contrary contained herein, within thirty (30) days after Tenantexercises the Option, Landlord shall provide Tenant with notice of the MarketRate as determined by Landlord pursuant to this Subparagraph (7)(b).  Within ten (10) business days after receiptof Landlord’s determination of the Market Rate, Tenant shall have the right todispute said determination upon written notice to Landlord.  In the event Tenant timely disputes Landlord’sdetermination, Landlord and Tenant shall attempt to resolve such dispute withinthirty (30) days after Tenant provides written notice of such dispute.  In the event Landlord and Tenant are unableto resolve such dispute within said thirty (30) day period, Tenant, as its soleand exclusive remedy, shall either: (i) accept Landlord’s determination of theMarket Rate; (ii) proceed to an arbitration procedure as outlined below, or(iii) elect to waive its exercise of the Option and the Original Lease shallterminate on the Termination Date.

(c)                                  ArbitrationProcedure.  If Tenant elects to exercisethe Option and have the Market Rate determined by Qualified Appraisers(provided that both parties have attempted in good faith to reach a mutuallyacceptable agreement, but were unable to do so), Landlord and

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Tenant shall eachwithin five (5) business days after Landlord’s receipt of the notice to proceedto arbitration to nominate and appoint a Qualified Appraiser to determine theMarket Rate.  Upon the appointment of thetwo (2) Qualified Appraisers, they shall be instructed to fairly andimpartially determine the Market Rate. The two (2) Qualified Appraisers shall afford to Landlord and Tenant theright to submit evidence with respect to such value and shall, with allpossible speed, make their respective determinations and deliver a writtenreport thereof to Landlord and Tenant within thirty (30) days after theirappointment.  If the two (2) QualifiedAppraisers are unable to agree upon the Market Rate, the Qualified Appraisersshall elect a third Qualified Appraiser within ten (10) days after theexpiration of such thirty (30) day period. Within ten (10) business days after the election of the third QualifiedAppraiser, a majority of the Qualified Appraisers will set the Market Rate forthe Option Term.  As used herein, theterm “Qualified Appraiser” means a commercial real estate broker who has beenactively and continuously engaged in the leasing of commercial office space inthe Southeast Suburban Submarket for not less than the previous  five (5) year period prior to suchappointment as his/her primary occupation, and is not affiliated with Landlordor Tenant.

(c)                                  UnlessLandlord is timely notified by Tenant in accordance with subparagraph (a)above, it shall be conclusively deemed that Tenant does not desire to exercisethe Option, and the Original Lease shall expire in accor­dance with its terms,on the Termination Date.

(d)                                 Tenant’sright to exercise its Option shall be conditioned on:  (i) Tenant not being in default under theLease at the time of exercise of the Option or at the time of the commencementof the Option Term; and (ii) Tenant not having subleased more than twenty-fivepercent (25%) of the New Pre­mises or assigned its interest under the Lease asof the commencement of the Option Term or having vacated more than twenty-fivepercent (25%) of the New Premises.

8.                                       Brokerage.  Tenant has no knowledge of any brokers’involvement in this transaction on behalf of Tenant, except The StaubachCompany, which has acted as Tenant’s leasing broker and shall be paid acommission pursuant to a separate agreement. Tenant will indemnify Landlord against any claim or expense (including,without limitation, attorneys’ fees) paid or incurred in connection with thisAmendment by Landlord as a result of any claim for commissions or fees by anyother broker, finder, or agent, whether or not meritorious, employed by Tenantor claiming by, through or under Tenant.

9.                                       General.  This Amendment is intended to be, and shallbe construed as, an amendment of the Original Lease.  To the extent that the terms and conditionsof this Amendment conflict with the terms and conditions of the Original Lease,the terms and conditions of this Amendment shall control.  Capitalized terms used in this Amendmentshall have the meaning ascribed to them in the Original Lease.  The Original Lease, as modified by this Amendment,may be referred to herein as the “**Lease**”**.**

10.                                 Successorsand Assigns.  This Amendment shall bebinding upon and shall inure to the benefit of the heirs, executors,administrators, successors and permitted assigns of the respective partieshereto.

11.                                 Counterparts.  This Amendment may be executed in severalcounterparts, each of which may be deemed an original, but all of whichtogether shall constitute one and the same 

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instrument.  The parties agree that signatures transmittedby facsimile or electronic mail shall be binding as if they were originalsignatures.

12.                                 Attorneys’Fees.  In the event it becomesnecessary for either party to file a suit to enforce this Amendment or anyprovisions contained herein, the party prevailing in such action shall recover,in addition to all other remedies or damages, reasonable attorneys’ fees andcourt costs incurred by such prevailing party in such suit.

IN WITNESS WHEREOF, the Landlord and Tenant haveexecuted this Amendment as of the date first above written.

 
| LANDLORD:                       |                                   | TENANT:                 |
|---------------------------------|----------------------------------------|-------------------------|
|                            |                                   |                    |
| WESTCORE  PYRAMID, L.P.,        |                                   | EVOLVING SYSTEMS, INC., |
| a Delaware  limited partnership |                                   | a Delaware corporation  |
|                            |                                   |                    |
| By:                             | WESTCORE DENVER  GP, LLC,              |                    | By: |   | /s/ Brian R. Ervine |
|                            | a Delaware  limited liability company, |                    |   |   |
|                            | its General  Partner                   |                    | Name: |   | Brian R. Ervine |
|                            |                                   |                    |   |   |
|                            | By:                                    | /s/ Don Ankeny          |   |   | Title: |   | CFO |
|                            |                                   | Don Ankeny              |   |   |
|                            |                                   | Authorized  Signatory   |   |   |
|                            |                                   |                    |   |   |
| Address:                        | 5975 South  Quebec Street, Suite 100   |                    | Address: | 9777 Pyramid Court, Suite 100 |
|                            | Centennial,  Colorado 80111            |                    |   | Englewood, CO 80112 |
|                            |                                   |                    |   |   |
| Phone:                          | (303) 721-7600                         |                    | Phone: | (303) 802-1000 |
| Fax:                            | (303) 721-1122                         |                    | Fax: | (303) 802-1138 |
|                                 |                                        |                         |  |  |  |  |  |  |  |  |  |  |

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**EXHIBIT A**

 

**FloorPlan**

12

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**EXHIBITB**

**Form ofLetter of Credit**

**LETTER OF CREDIT**

**Westcore Pyramid, L.P.5975 South Quebec Street, Suite 100Centennial, Colorado 80111Attention: John Fefley**

**Re:          Letterof Credit No.                                  **

**Ladies and Gentlemen:**

**By order of our client, Evolving Systems, Inc.(Applicant), we hereby issue in your favor our clean, unconditional irrevocableLetter of Credit which is available against presentation of your sightdraft.  The draft must be accompanied by:**

**1.**                                       This Letter of Credit No.                                  ;and

**2.**                                       Certification signed by anauthorized representative of                                                                   ,or an officer of its transferee or assignee, stating essentially as follows:

**“The undersigned Beneficiary requests payment of theenclosed draft under the enclosed Letter of Credit.”**

**This Letter of Credit shall be subject to theSpecial Conditions set forth on Exhibit 1, such exhibit being considered a parthereof and incorporated herein by reference.**

**We hereby agree that all drafts drawn under and incompliance with the terms of this credit shall meet with honor uponpresentation and delivery of documents on or before 5:00 p.m., Mountain Time                                  ,as specified to the drawee.**

** **
|    |   |               |
|---------|--------|--------------------|
| Attest: | a      |               |   |
|    |   |               |
|    |   |               |
| By:     |   |               |   | By: |   |   |
| Title:  |   |               | Title: |   |
|    |   |               |
|    |   | “Lender” |
|         |        |                    |  |  |  |  |  |

 

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Exhibit 1 to Exhibit I

**To Letter of Credit No.                       **

The Letter of Credit shall be governed by the following SpecialConditions:

a.                                       This Letter of Credit shall be governed byand construed in accordance with the laws of the State of Colorado, includingspecifically, but not limited to, C.R.S. 1973, ‘ 4-5-101,*et seq.*, entitled Uniform Commercial Code— Letters of Credit.

b.                                      Issuer agreesthat it may not defer honor beyond the close of the first banking day afterpresentment of a sight draft drawn hereunder and accompanying documents.

c.                                       This Letter ofCredit shall be transferable and assignable to any person or entity who is thesuccessor or assignee of Beneficiary’s interest under the Office Building Leasedated March 30, 1995, the current parties to which are Westcore Pyramid, L.P.,as Landlord and Evolving Systems, Inc., as Tenant.

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**EXHIBIT C**

**Pricing Plans**

NOTE: Pricing Plans include those alternate selections made at April 4,2007 meeting with Intergroup Architects and Landlord and Tenant representatives,as well as configuration of the selected area per the 3/4/2007 PreliminaryPlans-Option B of Intergroup Architects.

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