---

---

EXHIBIT 4.27

# CONFIDENTIAL TREATMENT 
REQUESTED PURSUANT TO
RULE 24b-2

Certain portions of this exhibit
have been omitted pursuant to a request for confidential treatment under Rule 24b-2 of the
Securities exchange Act of 1934. The omitted materials have been filed separately with the
Securities and Exchange Commission.

Execution version

# CONFIDENTIAL

# AMENDMENT #4

# TO

# OEM PURCHASE AND SALE
AGREEMENT NO. 011449

# BETWEEN SELLER
CORPORATION AND NORTEL NETWORKS LIMITED

This Amendment #4 to OEM Purchase and
Sale Agreement No. 011449 by and between Nortel Networks Limited, a Canada corporation
with offices located at 8200 Dixie Road, Suite 100, Brampton, Ontario, Canada L6T 5P6
(Nortel Networks) and AudioCodes Ltd., an Israeli corporation with offices located at 1
Hayarden Street, Airport City Lod, 70151 (Seller), will be effective as of April 28, 2005.

WHEREAS, Nortel Networks and Seller
entered into an OEM Purchase and Sale Agreement dated April 28, 2003, as amended
(Agreement); and

WHEREAS, Nortel Networks and Seller
wish to amend the Agreement for the purposes of adding Exhibits O and P, Exhibits A-4,
A-5, A-6 and A-8 and certain general terms and conditions;

Now, therefore, the parties agree to
amend the Agreement as follows:

|A. | Add
new Subsection 6.5 to the Agreement as follows:
|-- | ---------------------------------------------------

| | 6.5
Business Continuity Planning
| | ---------------------------------

| | 6.5.1 | Seller
represents and warrants that it will implement an effective business continuity plan to
be effective by January, 1st 2006 that will ensure that Seller is able to continue to
provide Products when the manufacture or delivery of Products isinterrupted for
any reason outside of Sellers reasonable control (BCP) and will
maintain and update the BCP at least annually during the Term for each of its
manufacturing and operations sites. Seller will perform a timely assessment after the
occurrence of any event that may delay production or shipping of Products for a period of
more than 10 business days. Seller will activate the BCP, if Seller determines as a
result of its assessment that a Seller site
will be unable to produce or ship Products for a period of more than 10 business days.
| | ----- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

PAGE 1 OF 12

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| | 6.5.2 | The
BCP will contain, at a minimum, provisions for (a) a risk assessment and business impact
analysis, (b) a prevention/mitigation plan, and (c) a resumption of services plan,
including a recovery/restoration plan. The preceding will cover, but not be limited to,
(i) Product documentation storage and protection (including, but not limited, to storage
of design documents, tools, process and fixtures), (ii) information systems security and
redundancy, and (iii) a detailed plan with relevant Contract Manufacturers to rapidly
recover the loss of Product manufacturing facilities or Product delivery capability.
| | ----- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

| | 6.5.3 | Seller
will provide a detailed outline of the BCP within 10 business days of Nortel Networks request
for the then-current BCP. Certain details of the BCP will not be shared between the
parties.
| | ----- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

| | 6.5.4 | Seller's
implementation of the BCP will be at no additional cost to Nortel Networks
| | ----- | -----------------------------------------------------------------------------------

| | 6.5.5 | At
Nortel Networks request and at no additional charge to Nortel Networks Seller will
participate in discussions initiated by Nortel Networks for purposes of evaluating and
coordinating and integrating the business continuity plans of its suppliers with Nortel
Networks overall business continuity plan.
| | ----- | -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

|B. | Add
new Subsection 23.11 to the Agreement as follows:
|-- | -----------------------------------------------------

| | 23.11 | Information Systems Security
 If Nortel Networks grants
Seller access to Nortel Networks information systems,Seller will safeguard
the security of Nortel Networks information systems, as set out in Exhibit O,
attached to and incorporated in this Agreement.
| | ------ | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

|C. | Add
new Exhibit O Information Systems Security to the Agreement,
               attached to and incorporated in this Amendment 4 as Attachment 1.
|-- | ---------------------------------------------------------------------------------------------------------------------------------------------------

|D. | Section
2.1.2 of Exhibit A-1 is hereby deleted in its entirety.
|-- | ---------------------------------------------------------------

|E. | The
tables labeled Vocoders Indemnification in Sections 2.2.1,
               2.2.2, 2.2.3, and 2.2.4 of Exhibit A-1 are hereby deleted in their
entirety.                However, it is noted that AudioCodes only offers Products under
this agreement                that support G.711, G.726, G.723.1 and G,.729A. This
Agreement does not cover                indemnification for other vocoders. Both parties
agree to discuss and mutually                agree on how to handle indemnity for
additional vocoders if these additional                vocoders are added as part of an
agreed change in the Specifications.
|-- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

|F. | The
two lines under the heading Indemnification appearing in the
               table in Section 2.2.5 of Exhibit A-1 are hereby deleted in their
entirety.                However, it is noted that AudioCodes only offers Products under
this agreement                that support G.711, G.726, G.723.1 and G,.729A. This
Agreement does not cover                indemnification for other vocoders. Both parties
agree to discuss and mutually                agree on how to handle indemnity for
additional vocoders if these additional vocoders are added as part of an agreed change in the Specifications.
|-- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

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|G. | Section
1(c) of Exhibit A-2 is hereby deleted in its entirety.  However,  it is noted that
AudioCodes only offers Products under this agreement that support G.711, G.726, G.723.1
and G,.729A. This Agreement does not cover indemnification for other vocoders. Both
parties agree to discuss and mutually agree on how to handle indemnity for additional
vocoders if these additional vocoders are added as part of an agreed change in the
Specifications.
|-- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

|H. | The
two lines under the heading Indemnification appearing in the
               table in Section 1.1 of Exhibit A-2 are hereby deleted in their entirety.
               However, it is noted that AudioCodes only offers Products under this
agreement                that support G.711, G.726, G.723.1 and G,.729A. This Agreement
does not cover                indemnification for other vocoders. Both parties agree to
discuss and mutually                agree on how to handle indemnity for additional
vocoders if these additional                vocoders are added as part of an agreed
change in the Specifications.
|-- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

|I. | The
following paragraph in Section 1 of Exhibit A-3, which is Attachment 1 to
               Amendment No. 1 effective May 1, 2003, is hereby deleted in its entirety:
|-- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------

| | With
respect to the cost reduction obligation described in Section 3 below, Seller is not
obligated in its cost reduction calculations to include the cost of indemnifying Nortel
Networks against third party intellectual property claims related to Nortel Networks
purchase of Product A0514478, which includes Voice Codec G.723.1 and G.729A. For purposes
of such cost reduction calculations the cost for Voice Codec indemnification included in
the Price for A0514478 is [*] per port per Codec.
| | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

|J. | For
the avoidance of doubt, the deletion of language and references to                Indemnification as
set forth in Articles D, E, F, G, H and I above                in no way modifies or
reduces Sellers obligation to provide                indemnification protection to
Nortel Networks under Section 18 of the Agreement.                However, it is noted
that AudioCodes only offers Products under this agreement                that support
G.711, G.726, G.723.1 and G,.729A. This Agreement does not cover
               indemnification for other vocoders. Both parties agree to discuss and
mutually                agree on how to handle indemnity for additional vocoders if these
additional                vocoders are added as part of an agreed change in the
Specifications.
|-- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

|K. | Add
new Exhibit A-4 Mediant 5000 Trunk Gateway Product to the
               Agreement, attached to and incorporated in this Amendment 4 as Attachment
2.
|-- | -----------------------------------------------------------------------------------------------------------------------------------------------------------

|L. | Add
new Exhibit A-5 M2K  CS2K DC Power Product to the
               Agreement, attached to and incorporated in this Amendment 4 as Attachment
3.
|-- | ----------------------------------------------------------------------------------------------------------------------------------------------------

|M. | Add
new Exhibit A-6 IPM2000  CS2K AC Powered Media Server                Product to
the Agreement, attached to and incorporated in this Amendment 4                as
Attachment 4.
|-- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

|[*]  Confidential
|-----------------

PAGE 3 OF 12

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|N. | Add
new Exhibit A-7 Mediant 1000 (MG3100)  H.248 and Mediant 1000
               (MG3100) -SIP to the Agreement, attached to and incorporated in this
               Amendment 4 as Attachment 5.
|-- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

|O. | Added
new Exhibit O Hazardous Materials Regulations to the
               Agreement, attached and incorporated in this Amendment 4 as Attachment 6.
|-- | -----------------------------------------------------------------------------------------------------------------------------------------------------

Except for this Amendment No. 4, in
all other respects the Agreement shall remain unchanged.

IN WITNESS WHEREOF, the parties have
caused this Amendment No. 4 to the Agreement to be signed by their duly authorized
representatives.

|                        |                       
|----------------------- | ----------------------
|
|
|
|
|NORTEL NETWORKS LIMITED | AUDIOCODES LTD.       
|                       
|                       
|By:                     | By: /s/ Ben Rabinowitz
|                       
|                       
|Name:                   | Name: Ben Rabinowitz  
|(Type/Print)            | (Type/Print)          
|                       
|                       
|Title:                  | Title: Vice President 
|                       
|                       
|Date:                   | Date: October 10, 2005

PAGE 4 OF 12

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# ATTACHMENT 1 
EXHIBIT O

# INFORMATION SYSTEMS
SECURITY

|1. | Access  Seller shall ensure that access and use (either on-site or
               remotely) of Nortel Networks Technology Resources by Seller or any
               non-Nortel Networks party performing under the Agreement (each an Outside
               Access Party)shall be limited only to access and use needed for
               performance. Technology Resources means network systems and services
               (voice and/or data) such as the Inter/Intranet gateways , electronic-mail and
               telephony and include, but are not limited to its computer systems, all system
               hardware, all hard drives, electronic media, storage areas, files and desks and
               information services (i.e. remote access, web/file servers & services,
               etc.). The Outside Access Party will provide Nortel Networks with the name of
               each of its personnel who will access Nortel Networks computer system
               during their performance under the Agreement (Authorized Workers).
               Authorized Workers will establish and maintain a unique identifier for access
               and follow the same computer system security rules as Nortel Networks personnel.
               The security requirements will also apply to Authorized Workers access and
               use of Nortel Networks electronic mail system, electronic switched
               network, (either directly or via a direct inward service access [DISA] feature)
               or any other Nortel Networks property, equipment or service.
|-- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

| | Unless
explicitly authorized in writing by Nortel Networks, Outside Access Party must not (i)
attempt to reverse engineer, disassemble, reverse translate, decompile or in any other
manner decode any element of the Technology Resources; (ii) make modifications,
enhancements, adaptations or translations, in whole or in part, to or of any element of
the Technology Resources; (iii) make copies of any element of the Technology Resources;
(iv) probe host computers or networks; (v) breach or examine the security controls of a
host computer, network component or authentication system; (vi) monitor data on any
network or system; (vii) interfere with the service of any user, host or network, or
overload a server, network connected device, or network component; (viii) originate
malformed data or network traffic that results in damage to, or disruption of, a service
or network connected device; (ix) forge data or misrepresent the origination of a user or
source.
| | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

|1.1 | Failure
of Access-Outside Access Party understands that its access to and use of the
Technology Resources may from time to time be interrupted due to circumstances within or
outside the reasonable control of Nortel Networks. Nothing in this Agreement shall be
considered a promise or covenant to deliver access to the Technology Resources. Aside
from the access as provided herein, no license of any patent, copyright, or any other
right in respect of the Technology Resources is granted to Outside Access Party by virtue
of access to the Technology Resources.
|--- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

|1.2 | Waiver
of Liability  Notwithstanding any terms and conditions in this Agreement,
Nortel Networks hereby excludes all representations, warranties and conditions, express
or implied, including any representations, warranties or conditions of accuracy,
sufficiency, suitability or non-infringement. Outside Access Party hereby waives any
liability on the part of Nortel Networks for any damages, losses or expenses incurred by
Outside Access Party as a result of Outside Access Partys access to and use of the
Technology Resources (including, without limitation, the inadvertent accessing of a
computer virus or other harmful computer file or program) or failure to access the
Technology Resources, whether arising in contract, tort or otherwise.
|--- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

|1.3 | Confidential
Information and Personal Data  All passwords, identification numbers and
information obtained during the Outside Access Partys use of Nortel Networks Technology
Resources are Confidential Information.
|--- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

|1.4 | Unauthorized
Access  The Outside Access Party will cooperate in the investigation of any
apparent unauthorized access to Nortel Networks customers or any activity resulting
in a security breach as defined under Nortel Networkscorporate policies, procedures
or standards.
|--- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

PAGE 5 OF 12

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|2. | Segregation
Wall Using procedures documented for                Nortel
Networks by Contractor and reviewed and approved by Nortel Networks               security
team, the Outside Access Party will ensure that Authorized Workers
               implement effective isolation and containment procedures (for example
separate                password protected folders or storage media that facilitates
separation and                prevents open access or disclosure to non -authorized
workers or third party                companies) for the protection of Nortel Networks
technologies and intellectual                properties to ensure non-disclosure, held in
confidence, by its personnel who                are assigned to the account of a known or
potential Nortel Networks competitor                (Competitors). The Outside Access
Party must implement procedures to logically                segregate, by normal
commercial means, all Nortel Networks information, data and                communications
(including, but not limited to Confidential Information) from                Competitors
and Outside Access Party personnel who are not Authorized Workers
               (Segregation Wall).
|-- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

|3. | Inadequate
Security  If Nortel Networks notifies the                Outside
Access Party that the Segregation Wall is not working and makes a
               reasonable request to change or replace the Segregation Wall; the Outside
Access                Party will comply with Nortel Networks request
|-- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

|3.1 | Security
Audit Under Section 9.6 of this Agreement Nortel Networks may audit the
Segregation Wall. In addition to the rights and obligations set out in Section 9.6
Outside Access Party hereby grants Nortel Networks reasonable access to those of its
computer facilities that it uses or intends to use in association with the accessing the
Technology Resources for the purposes of assessing the on-going adequacy of Outside
Access Partys security measures and procedures in effect on such computer
facilities, and shall assist and co-operate with Nortel Networks in carrying out any such
assessment. If Nortel Networks determines that Outside Access Partys security
measures and procedures are inadequate to prevent unauthorized access to or use of the
Technology Resources, Nortel Networks may immediately deny further access until Outside
Access Party takes such measures as Nortel Networks may reasonably require.
|--- | -----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

|3.2 | Notice
of Security Breach  The Outside Access Party will promptly notify Nortel
Networks in writing in the event (a) there is a general breach of security, the
appearance of a breach or a breach attempt at the Outside Access Partys facilities
that may be involved in performing under the Agreement; or, (b) Outside Access Party
personnel (that are not Authorized Workers) or third parties breach the Segregation Wall.
At its expense the Outside Access Party will do whatever is necessary to preserve the
integrity of the Technology Resources and Confidential Information and correct the breach
and prevent it from recurring.
|--- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

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# ATTACHMENT 2 
Exhibit A-4 
Mediant 5000 Trunk
Gateway Product

|HA
Mediant 5000 VoIP in a N+1 Redundant Bearer Configuration
|------------------------------------------------------------

|MG5000                             | Mediant 5000 Redundant Base                             | [*]
|---------------------------------- | ------------------------------------------------------- | ---
|TP1610B                            | TP1610B cPCI 16 E1/T1, cPSB, IP                         | [*]
|TP1610B/HALF                       | TP1610B/HALF cPCI 16 E1/T1, cPSB, IP                    | [*]
|HW/RTM/2TELCO/CPSB/APB             | RTM for TP1610,cPSB, active board (one per "N" Board)   | [*]
|HW/RTM/REDUNDANCY/CPSB/APB         | RTM for TP1610,cPSB, standby board (one per "+1" Board) | [*]
|TP6310A/2016/OC-3                  | TP6310, 1xOC-3, 2016 Channels                           | [*]
|TP6310A/2016/OC-3/HALF             | TP6310, 1xOC-3, Half, 2016 G711 Channels                | [*]
|HW/RTM/OC-3/CPSB/APB               | RTM for TP-6310, 1 OC-3                                 | [*]
|HW/RTM/REDUNDANCY/6310/CPSB/APB    | RTM for TP6310,cPSB,standby board ("+1" board)          | [*]
|SW/EMS/Server (One per EMS Server) | EMS Server s/w license.                                 | [*]

 Cost Reduction
year over year     [*]

# Available Software
Options:

|DUA                 | SigTran-based DUA (per active board)                                     | [*]
|------------------- | ------------------------------------------------------------------------ | ---
|SW/IP-Sec           | IP-Sec for OAM/Call Control (per active board)                           | [*]
|SW/BearerEncryption | Bearer Encryption (per active board)                                     | [*]
|SW/PacketCable      | PacketCable Package (TGCP) not incl bearer encryption (per active board) | [*]
|SW/M2UA/SIGTRAN/2   | M2UA Sigtran Interworking SW (per 2 channels) Max of 8 links per board   | [*]

Notes -AudioCodes does not provide
the EMS hardware, only a license to use our EMS server software. EMS can support up to 100
Mediant 5000s.

Price reductions on TP6310 will not
occur until April, 2007, unless mutually agreed

In certain deployments of Mediant
5000, the fees, terms and the cap on support payments may not apply if AudioCodes is requested to provide support
beyond that is required in the Agreement

|M5K (MG3500) FRUs | PEC | Price
|----------------- | --- | -----

|HW/ES-1/NN                    | NTRX51XJ | [*]
|----------------------------- | -------- | ---
|HW/RTM/LIM-1/NN               | NTRX51XV | [*]
|HW/SC-2/NN                    | NTRX51XT | [*]
|HW/SA1C/RTM/ALARM/NN          | NTRX51XH | [*]
|HW/FM-2/NN                    | NTRX51XP | [*]
|HW/PS-2/AC/NN                 | NTRX51XR | [*]
|HW/PS-2/DC/NN                 | NTRX51XQ | [*]
|HW/AF-2/NN                    | N/A      | [*]
|HW/PEM-1/DC/NN                | NTRX51XK | [*]
|HW/APM-2/DC/NN                | NTRX51XN | [*]
|HW/PEM-1/AC/NN                | NTRX51XL | [*]
|HW/APM-2/AC/NN                | NTRX51XM | [*]
|HW/RTM/TP1610/ACTIVE/NN       | NTRX51XF | [*]
|HW/RTM/TP1610/STDBY/NN        | NTRX51XG | [*]
|HW/TP1610B/480/16SPAN/NN      | NTRX51XE | [*]
|HW/TP1610B/480/16SPAN/G711/NN | NTRX51XD | [*]
|HW/GP5000/Mediant/NN          | NTRX51XC | [*]

[*] Confidential

PAGE 7 OF 12

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Lab Hardware M5K In
coordination with Amendment #011449 to OEM Purchase and Sale Agreement No. between the
parties, Seller will provide Nortel Networks with up to [*] lab units free for internal
and external customer labs or trials at Nortel Networks discretion.  
At least three (3) of these free M5K units are to be used for external customers and both
parties must mutually agree on which Nortel Network customers will receive these M5K
units. Any units provided for free in calendar year 2005 will be counted in meeting this
obligation. For any further internal lab requirements Seller will provide an incremental
[*] off Nortel contracted price.  Requests for lab hardware are to be
made in writing by the relationship prime.

PAYMENT TERMS: [*]

PAGE 8 OF 12

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# ATTACHMENT 3

# Exhibit A-5

# M2K  CS2K DC
Power Product

# M2K  CS2K Pricing
for DC Power:

|Part Number                   | Description                            | Price
|----------------------------- | -------------------------------------- | -----
|Mediant2000/1Span/DC/H248/NN  | Mediant 2000, 1 span, DC power, H.248  | [*]  
|Mediant2000/2Span/DC/H248/NN  | Mediant 2000, 2 span, DC power, H.248  | [*]  
|Mediant2000/4Span/DC/H248/NN  | Mediant 2000, 4 span, DC power, H.248  | [*]  
|Mediant2000/8Span/DC/H248/NN  | Mediant 2000, 8 span, DC power, H.248  | [*]  
|Mediant2000/16Span/DC/H248/NN | Mediant 2000, 16 span, DC power, H.248 | [*]  

[*] Confidential

PAGE 9 OF 12

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# ATTACHMENT 4

# Exhibit A-6

# IPM2000  CS2K AC
Powered Media Server Product

|Part Number                  | Description                                     | Price
|---------------------------- | ----------------------------------------------- | -----
|IPM2K/IVR/LI/TT/120/2AC      | IPMedia 2000, 120 port AC Power                 | [*]  
|IPM2K/IVR/LI/TT/240/2AC      | IPMedia 2000, 240 port AC Power                 | [*]  
|IPM2K/IVR/LI/TT/CONF/120/2AC | IPMedia 2000, 120 port Conferencing AC Power    | [*]  
|IPM2K/IVR/LI/TT/CONF/240/2AC | IPMedia 2000, 240 port AC Conferencing AC Power | [*]  

[*] Confidential

PAGE 10 OF 12

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# ATTACHMENT 5 
Exhibit A  7

|Mediant 1000 (MG 3100) - H.248 | Hardware Price | SIP Charge | Total
|------------------------------ | -------------- | ---------- | -----
|Mediant1000/1Span/2AC/H248/NN  | [*]            | [*]        | [*]  
|Mediant1000/2Span/2AC/H248/NN  | [*]            | [*]        | [*]  
|Mediant1000/4Span/2AC/H248/NN  | [*]            | [*]        | [*]  
|                               | [*]            | [*]        | [*]  
|Mediant1000/1Span/DC/H248/NN   | [*]            | [*]        | [*]  
|Mediant1000/2Span/DC/H248/NN   | [*]            | [*]        | [*]  
|Mediant1000/4Span/DC/H248/NN   | [*]            | [*]        | [*]  

|Mediant 1000 (MG 3100) - SIP |     |     |    
|---------------------------- | --- | --- | ---
|Mediant1000/1Span/2AC/SIP/NN | [*] | [*] | [*]
|Mediant1000/2Span/2AC/SIP/NN | [*] | [*] | [*]
|Mediant1000/4Span/2AC/SIP/NN | [*] | [*] | [*]
|                             | [*] | [*] | [*]
|Mediant1000/1Span/DC/SIP/NN  | [*] | [*] | [*]
|Mediant1000/2Span/DC/SIP/NN  | [*] | [*] | [*]
|Mediant1000/4Span/DC/SIP/NN  | [*] | [*] | [*]

[*] Confidential

PAGE 11 OF 12

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# ATTACHMENT 6

# Exhibit O

# HAZARDOUS MATERIALS
REGULATIONS

Seller will notify Nortel Networks
about the hazardous and toxic materials, as required of it by the regulations promulgated
under all applicable laws, rules and regulations of any applicable governmental entity
including, without limitation, the following U.S. and E.U. laws:

|(a) | U.S. laws  The Toxic Substances Control Act, Resource Conservation and
          Recovery Act of 1976, Hazardous Materials Transportation Act, Occupational
          Safety and Health Act of 1970, Comprehensive Environmental Response,
          Compensation and Liability Act of 1980, Consumer Product Safety Act, Radiation
          Control for Health and Safety Act of 1968, Clean Air Act, and Clean Water Act ,
          and
|--- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

|(b) | E.U. laws  The following European Union Environmental Directives:
          Eco-design of Energy Using Product (EuP), Waste from Electrical and Electronic
          Equipment (WEEE) directive (effective August 2005) and Restriction on Use of
          Certain Hazardous Substances (RoHS) (effective July 2006) directive. With
          respect to the RoHS Directive, Seller must be able to demonstrate to Nortel
          Networks satisfaction by May 30, 2006 that no lead, hexavalent chromium
          cadmium, mercury or polybrominated biphenyls (PBB)/polybrominated diphenyl
          ethers (PBDE) are present in any product covered by the ROHS Directive used or
          provided by Seller in providing the Products in the EU, except where exemptions
          allowing the use of such substances apply under applicable law. Seller shall
          monitor the implementation and local requirements of WEEE in relevant EU
          countries and shall inform and discuss with Nortel Networks on a timely basis of
          its plan regarding implementation and management of the WEEE and RoHS directives
          for Nortel Networks review and further discussion..
|--- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

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