ASSIGNMENT, ASSUMPTION, AND AMENDMENT OF SUBLEASE

Exhibit 99.4

ASSIGNMENT, ASSUMPTION, AND AMENDMENT OF SUBLEASE

     THIS ASSIGNMENT, ASSUMPTION, AND AMENDMENT OF SUBLEASE (this “Agreement”), is entered into as of the 30th day of August, 2006, by and between NUASIS CORPORATION, a Delaware corporation (“Assignor”), INTERVOICE, INC., a Texas corporation (“Assignee”) and PAYPAL, INC., a Delaware corporation (“Sublandlord”).

WITNESSETH:

     WHEREAS, Sublandlord and Bryant Street Associates, LLC, a California limited liability company (“Original Prime Landlord”), entered into that certain Lease dated as of August 15, 2001 covering approximately 50,210 square feet of space in the building known as 303 Bryant Street in the City of Mountain View, California (the “Building”), as more particularly described therein, which Lease has been amended by that certain First Addendum of Lease dated October 30, 2001 pursuant to which the leased premises was expanded to 54,188 square feet (such Lease, as amended by such First Addendum of Lease, the “Prime Lease”);

     WHEREAS, 303 Bryant Street, LLC a Delaware limited liability company, is the current owner of the Building and the landlord under the Prime Lease (“Prime Landlord”);

     WHEREAS, Assignor and Sublandlord entered into that certain Sublease dated as of March 30, 2004 (the “Sublease”), covering approximately 25,879 rentable square feet of space (the “Sublease Premises”) located in the Building, as more particularly described in the Sublease;

     WHEREAS, Assignee intends to acquire substantially all of the assets of Assignor, including the Sublease (the “Acquisition”);

     WHEREAS, in connection with the Acquisition, Assignor desires to assign its right, title and interest in and to the Sublease to Assignee, and Assignee desires to assume Assignor’s right, title and interest in and to the Sublease;

     WHEREAS, Sublandlord, in consideration of the amendments to the Sublease set forth below, has agreed to consent to the above-described assignment and assumption and, subject to the terms contained herein, to release Assignor from liability under the Sublease accruing from and after the Effective Date (hereinafter defined);

     WHEREAS, as of the Effective Date, the parties desire to amend the term of the Sublease, and to provide for Assignee to have an option to extend the term of the Sublease for an additional term to expire on June 30, 2012;

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

1. Assignment and Assumption . Effective as of the later of (i) the date on which the closing of the Acquisition occurs, or (ii) the date on which Prime Landlord consents to the Assignment

(hereinafter defined) (such later date, the “Effective Date”), Assignor hereby assigns, conveys, transfers and sets over unto Assignee all of Assignor’s right, title and interest in, to and under the Sublease (including without limitation Assignor’s rights under Sections 19, 20, 22, 23, and 25), and Assignee hereby accepts said assignment of the Sublease from Assignor and, subject to the terms of this Agreement, assumes all duties, obligations and liabilities of Assignor under the Sublease arising from and after the date hereof (such assignment and assumption, the “Assignment”).

2. Consent of Sublandlord . In consideration of the terms and provisions hereinafter set forth, Sublandlord hereby consents to the Assignment. By consenting to the Assignment, Sublandlord undertakes no obligation to consent to any further assignment of the Sublease or to any future subleases of any part of the Sublease Premises. Notwithstanding Sublandlord’s consent to the Assignment, Sublandlord acknowledges that Assignee is a Permitted Transferee pursuant to Section 7(c)(i) of the Sublease.

3. Release . The parties acknowledge that certain rent and other charges are past due under the Sublease. Accordingly, Sublandlord has drawn $125,000.00 from the Letter of Credit pursuant to Section 18 of the Sublease and applied the same to the past due amounts under the Sublease. Assignee shall pay to Sublandlord the additional amount of $128,250.49 on or before the Effective Date. Upon such payment, Sublandlord agrees that effective on the Effective Date, (i) all amounts due under the Sublease through August 31, 2006 shall be deemed paid in full, and (ii) Assignor shall be released from any and all actions, causes of action, judgments, executions, suits, claims, demands, liabilities, damages and expenses arising under the Sublease after the Effective Date. In no event shall Assignor or Assignee be required to restore or renew the Letter of Credit. In the event the Effective Date occurs after August 31, 2006, within five (5) days after the Effective Date, Assignee shall pay to Sublandlord all Base Rent and other amounts owing under the Sublease with respect to the period from September 1, 2006, through the Effective Date.

4. Representations .

     (a)  Sublandlord Representations . Sublandlord represents to Assignee that (i) the Prime Lease is in full force and effect, and has not been further amended; (ii) the Sublease is in full force and effect, and has not been amended; (iii) to Sublandlord’s best knowledge, no default exists on the part of Sublandlord under the Prime Lease or the Sublease, nor, except as provided below, does there exist any event which, with the giving of notice or passage of time or both, could constitute such a default or event of default, (iv) to Sublandlord’s best knowledge, there are no pending or threatened actions, suits or proceedings before any court or administrative agency against Sublandlord which could, in the aggregate, adversely affect the Sublease Premises or the ability of Sublandlord to perform its obligations under the Sublease, and Sublandlord is not aware of any facts which might result in any actions, suits or proceedings, and (v) except for the past due amounts described in Section 3 above, to Sublandlord’s best knowledge no default exists on the part of Subtenant under the Sublease, nor does there exist any event which, with the giving of notice or passage of time or both, could constitute such a default. Approximately three years ago, Original Prime Landlord claimed that Sublandlord is obligated to include in the premises covered by the Prime Lease certain ground floor retail space in the Building. Sublandlord disputed such claim, but is currently paying rent thereon with a reservation of rights.

     (b)  Assignor Representations . Assignor represents to Sublandlord that (i) to Assignor’s best knowledge, no default exists on the part of Assignor (except with regard to the past due amounts described in Section 3 above) under the Sublease, nor does there exist any event which, with the giving of notice or passage of time or both, could constitute such a default or event of default, and (ii) to Assignor’s best knowledge, there are no pending or threatened actions, suits or proceedings before any court or administrative agency against Assignor which could, in the aggregate, adversely affect the Sublease Premises, and Assignor is not aware of any facts which might result in any actions, suits or proceedings.

5. Amendment of Sublease .

     (a)  Temporary Term . Effective on the Effective Date, the term of the Sublease shall be amended to expire on the date which is six (6) months following the Effective Date (such six (6) month period, the “Temporary Term”). At any time after the first sixty (60) days of the Temporary Term, either Assignee or Sublandlord may give notice to the other of its intention to terminate the Sublease prior to the natural expiration of the Temporary Term, which termination date shall be specified in such notice; provided, however, such termination date shall be at least thirty (30) days after the date the termination notice is delivered to the non-terminating party. However, neither party may terminate the Sublease under this Section 5(a) if, prior to the non- terminating party’s receipt of such termination notice, Assignee has exercised its Renewal Option (hereinafter defined).

     (b)  Rent During Temporary Term . Effective on the Effective Date, the schedule of Base Rent set forth in Section 3(a) of the Sublease shall be deleted in its entirety. During the Temporary Term, prior to the expiration or termination of the Sublease in accordance with Section 5(a) above or the occurrence of the Extended Term Commencement Date (as defined in Section 5(c) below), as applicable, the Base Rent payable under the Sublease shall be equal to $1.20 per month per rentable square foot of the Sublease Premises (i.e., $31,054.80 per month). Rent Adjustment, Maintenance Costs and all other charges under the Sublease shall be payable during the Temporary Term as set forth in the Sublease.

     (c)  Renewal Option . Section 24 of the Sublease is hereby deleted in its entirety. At any time during the Temporary Term, provided neither party has notified the other of its exercise of its right to terminate the Sublease, Assignee shall have the option to extend the term of the Sublease to expire on June 30, 2012 (the “Renewal Option”). Assignee may exercise such option by giving written notice thereof to Sublandlord, and upon such exercise, (i) the term of the Sublease shall be automatically extended to expire on June 30, 2012 (the “Expiration Date”) (and the Temporary Term shall be deemed terminated), and (ii) neither party shall have any further right to terminate the Sublease pursuant to subsection (a) above. In the event Assignee fails to exercise the Renewal Option on or before the end of the Temporary Term, then the Sublease shall expire at the end of the Temporary Term. The period from the date of Assignee’s exercise of the Renewal Option until the Expiration Date is hereinafter called the “Extended Term”. The date on which Assignee exercises the Renewal Option is hereinafter called the “Extended Term Commencement Date” or “ETCD”. Promptly after Assignee’s exercise of the Renewal Option, Sublandlord and Assignee shall execute a written agreement acknowledging such exercise of the Renewal Option; however, the term of the Sublease shall be extended on the Extended Term

Commencement Date, notwithstanding the failure of Sublandlord and Assignee to enter into such agreement. If Assignee does not exercise the Renewal Option on or before the expiration of the Temporary Term, such Renewal Option shall be deemed waived.

     (d)  Rent During Extended Term .

          (i) If the Extended Term Commencement Date occurs on or before the sixtieth (60th) day of the Temporary Term, then the Base Rent during the Extended Term shall be as follows:

For purposes of the foregoing sched