Document:

<PAGE>
                                                                    Exhibit 4.20

THIS AMENDING AGREEMENT is made as of the 26th day of June, 2006

BETWEEN:

            MITEL NETWORKS CORPORATION, a corporation incorporated under the
            laws of Canada (the "CORPORATION")

                                      -and-

            EDGESTONE CAPITAL EQUITY FUND II-B GP, INC., as agent for EdgeStone
            Capital Equity Fund II-A, L.P. and its parallel investors, and
            EDGESTONE CAPITAL EQUITY FUND II NOMINEE, INC., as nominee for
            EdgeStone Capital Equity Fund II-A, L.P. and its parallel investors
            (collectively "EDGESTONE")

                                      -and-

            ZARLINK SEMICONDUCTOR INC., a corporation incorporated under the
            laws of Canada ("ZARLINK")

                                      -and-

            POWER TECHNOLOGY INVESTMENT CORPORATION, a corporation incorporated
            under the laws of Canada ("PTIC")

                                      -and-

            WESLEY CLOVER CORPORATION, a corporation incorporated under the laws
            of Newfoundland ("WCC")

                                      -and-

            TERENCE H. MATTHEWS, an individual residing in the City of Ottawa,
            Province of Ontario ("MATTHEWS")

<PAGE>

                                      -and-

            CELTIC TECH JET LIMITED, a corporation incorporated under the laws
            of Canada ("CTJL")

RECITALS:

A.    The Corporation, EdgeStone, Zarlink, PTIC, WCC, Matthews, Mitel Knowledge
      Corporation and Mitel Systems Corporation entered into a shareholders
      agreement dated as of April 23, 2004 (the "SHAREHOLDERS AGREEMENT") to
      record their agreement as to the manner in which the Corporation's affairs
      would be conducted and to grant to each other certain rights and
      obligations with respect to their ownership, directly and indirectly, of
      the shares of the Corporation; subsequently, Mitel Knowledge Corporation
      dissolved, Mitel Systems Corporation was continued into WCC and CTJL
      became a party to such shareholders agreement.

B.    The Parties have agreed to amend the Shareholders Agreement in accordance
      with Section 11.9 of the Shareholders Agreement and the terms and
      conditions of this amending agreement (the "AMENDING Agreement").

THEREFORE, the Parties agree as follows:

1.    All capitalized terms which are used and not defined in this Amending
      Agreement shall have the meaning ascribed thereto in the Shareholders
      Agreement.

2.    Section 6.6(a) of the Shareholders Agreement is hereby deleted in its
      entirety and replaced with the following:

      (a)   Subject to Section 6.10, if, on or prior to May 1, 2007 (the "2007
            PUT DATE"), the Corporation has not completed an Initial Public
            Offering, Zarlink shall have the right, exercisable for a period of
            ninety (90) days after the 2007 Put Date (the "ZARLINK PUT PERIOD"),
            but not the obligation, to send a notice (the "ZARLINK PUT NOTICE")
            to the Corporation requiring the Corporation to purchase all or any
            portion of the 10,000,000 Common Shares (subject to appropriate
            adjustment for share dividends, share splits, capital
            reorganization, combinations and the like) (the "ZARLINK PURCHASED
            SECURITIES") held by Zarlink, upon and subject to the terms and
            conditions set out in this Section 6.6.

3.    Section 6.7(a) of the Shareholders Agreement is hereby deleted in its
      entirety and replaced with the following:

      (a)   Subject to Section 6.10, if, on or prior to the 2007 Put Date, the
            Corporation has not completed an Initial Public Offering, PTIC shall
            have the right, exercisable for a period of ninety (90) days after
            the 2007 Put Date (the "PTIC PUT PERIOD"), but

<PAGE>

            not the obligation, to send a notice (the "PTIC PUT NOTICE") to the
            Corporation requiring the Corporation to purchase all or any portion
            of the 16,000,000 Series B Shares (subject to appropriate adjustment
            for share dividends, share splits, capital reorganizations,
            combinations or the like) held by PTIC, or the Common Shares issued
            on the conversion thereof (the "PTIC PURCHASED SECURITIES"), upon
            and subject to the terms and conditions set out in this Section 6.7.

4.    The definition of "2006 Put Date" in the section entitled "Definitions" in
      Appendix I of the Shareholders Agreement is hereby deleted in its entirety
      and replaced with the following:

      "2007 PUT DATE" has the meaning set forth in Section 6.6(a);

5.    The foregoing is without any prejudice to any rights of the Parties under
      any agreements with the Corporation except as specifically set forth
      herein and except as otherwise provided in this Amending Agreement, all
      terms and conditions of the Shareholders Agreement shall continue in full
      force and effect.

6.    The Parties shall, with reasonable diligence, do all such things and
      provide all such further documents or instruments required by any other
      Party as may be reasonably necessary or desirable to effect the purpose of
      this Amending Agreement and carry out its provisions.

7.    This Amending Agreement shall be construed in accordance with the laws of
      the Province of Ontario and the laws of Canada applicable therein and
      shall be treated in all respects as an Ontario contract.

8.    This Amending Agreement shall only be effective once executed by all
      parties hereto, shall not be binding on any party until executed by all
      parties hereto and may be executed by the Parties in counterparts and may
      be executed and delivered by facsimile and all such counterparts and
      facsimiles shall together constitute one and the same agreement.

<PAGE>

IN WITNESS OF WHICH the Parties have duly executed this Amending Agreement.

                                   MITEL NETWORKS CORPORATION

                                   By: /s/ STEVE SPOONER
                                       ------------------------------------
                                       Name: Steve Spooner
                                       Title: Chief Financial Officer

<PAGE>

                                   EDGESTONE CAPITAL EQUITY FUND
                                   II-B GP, INC., AS AGENT FOR EDGESTONE
                                   CAPITAL EQUITY FUND II-A, L.P. AND ITS
                                   PARALLEL INVESTORS

                                   By: /s/ GUTHRIE STEWART
                                       -----------------------------------------
                                       Name: Guthrie Stewart
                                       Title: Executive Vice President & Partner

                                   EDGESTONE CAPITAL EQUITY FUND II
                                   NOMINEE, INC., AS NOMINEE FOR EDGESTONE
                                   CAPITAL EQUITY FUND II-A, L.P. AND ITS
                                   PARALLEL INVESTORS

                                   By: /s/ GUTHRIE STEWART
                                       -----------------------------------------
                                       Name: Guthrie Stewart
                                       Title: Executive Vice President & Partner

<PAGE>

                                   ZARLINK SEMICONDUCTOR INC.

                                   By: /s/ DON MCINTYRE
                                       -----------------------------------------
                                       Name: Don McIntyre
                                       Title: Senior Vice President

<PAGE>

                                   POWER TECHNOLOGY INVESTMENT CORPORATION

                                   By: /s/ LESLIE RAENDEN
                                       -----------------------------------------
                                       Name: Leslie Raenden
                                       Title: Executive Vice President, Finance

<PAGE>

                                   WESLEY CLOVER CORPORATION

                                   By: /s/ JOSE MEDEIROS
                                       -----------------------------------------
                                       Name: Jose Medeiros
                                       Title: President

                                   CELTIC TECH JET LIMITED

                                   By: /s/ JOSE MEDEIROS
                                       -----------------------------------------
                                       Name: Jose Medeiros
                                       Title: President

<PAGE>

SIGNED, SEALED AND DELIVERED  )
in the presence of:           )
                              )
                              )
/s/ SIMON J. GIBSON           )         /s/ DR. TERENCE H. MATTHEWS
-------------------------               ----------------------------------------
Witness                       )         Dr. TERENCE H. MATTHEWS
                              )<PAGE>
                                                                    Exhibit 4.38

(TECHNOLOGY PARTNERSHIPS CANADA LOGO)           TARTENARIAT TECHNOLOGIQUE CANADA

An Agency of Industry Canada                    Un organisme d'Industrie Canada

                                                      TPC PROJECT NO. 720-481443
                                                                 AMENDMENT NO. 2

                         TECHNOLOGY PARTNERSHIPS CANADA

                               AMENDMENT AGREEMENT

THIS AGREEMENT made

BETWEEN: HER MAJESTY THE QUEEN IN RIGHT OF CANADA,
         as represented by the Minister of Industry
         (hereinafter referred to as the "MINISTER")

AND:     MARCH NETWORKS CORPORATION
         (hereinafter referred to as "a PROPONENT" or "MARCH NETWORKS").

AND:     MITEL NETWORKS CORPORATION
         (hereinafter referred to as "a PROPONENT" or "MITEL NETWORKS")

AND:     MITEL KNOWLEDGE CORPORATION
         (hereinafter referred to as "a PROPONENT" or "MITEL KNOWLEDGE")

Collectively referred to as "the PROPONENTS".

INTRODUCTION

(i)  The Minister and the Proponents entered into a Contribution Agreement dated
     the 10th day of October, 2002 under the Technology Partnerships Canada
     Program (the "Contribution Agreement"); and

(ii) The Contribution Agreement was amended by letter dated March 27, 2003, now
     called Amendment Number 1; and

(iii) The Minister and the Proponents now wish to amend the Contribution
     Agreement.

IN CONSIDERATION OF THEIR RESPECTIVE OBLIGATIONS SET OUT IN THE CONTRIBUTION
AGREEMENT, THE PARTIES AGREE TO AMEND THE CONTRIBUTION AGREEMENT AS FOLLOWS:

(CANADA LOGO)                                                          (GRAPHIC)

<PAGE>

                                                                          Page 2

1.   This Amendment must be signed by the Recipient and received by the Minister
     within thirty (30) days of its signature on behalf of the Minister, failing
     which it will be null and void.

2.   In Article 3.2:

     DELETE:  the date "September 30th, 2004"; and
     REPLACE: with the date "March 31st, 2005".

3.   In Article 4.3:

     DELETE:  the Fiscal Year Contribution amounts in their entirety; and
     REPLACE: with the following Fiscal Year Contribution amounts:

               "2002/2003             $29,577,660
                2003/2004             $15,440,000
                2004/2005             $14,982,340".

4.   In Article 7.2:

     DELETE:  the name "Dr. Donald Mills" and the title "Chief Operating
              Officer" for March Networks Corporation, and
     REPLACE: with the name "Peter Strom" and the title "President and Chief
              Executive Officer".

5.   In Article 8.1:

     DELETE:  the date "September 30th, 2004"; and
     REPLACE: with the date "March 31st, 2005".

6.   In Schedule 8, Article 4.8:

     DELETE:  the name "Dr. Donald Mills" and the title "Chief Operating
              Officer" for March Networks Corporation, and
     REPLACE: with the name "Peter Strom" and the title "President and Chief
              Executive Officer".

<PAGE>

                                                                          Page 3

IN WITNESS WHEREOF the parties hereto have executed this Amendment Agreement
through duly authorized representatives.

HER MAJESTY THE QUEEN IN RIGHT
OF CANADA, as represented by the Minister of Industry

Per: /s/ Denise Cuevremont              Apr. 27, 2004
     -------------------------------    Date
     Technology Partnerships Canada

     DENISE CUEVREMONT - DIRECTOR
     Name & Title

MARCH NETWORKS CORPORATION]

Per: /s/ Peter Strom                    May 02, 2004
     -------------------------------    Date
     Peter Strom President/CEO
     Name & Title

MITEL NETWORKS CORPORATION]

Per: /s/ Don Smith                      29 April, 2004
     -------------------------------    Date
     DON SMITH, CEO
     Name & Title

MITEL KNOWLEDGE CORPORATION]

Per: /s/ Jose Medeiros                  April 30, 2004
     -------------------------------    Date
     JOSE MEDEIROS, CFO
     Name & Title

<PAGE>

(TECHNOLOGY PARTNERSHIPS CANADA LOGO)           PARTENARIAT TECHNOLOGIQUE CANADA

An Agency of Industry Canada                    Un organisms d'Industrie Canada

                                                      TPC PROJECT NO. 720-481443
                                                                  AMENDMENT NO.3

                         TECHNOLOGY PARTNERSHIPS CANADA

                               AMENDMENT AGREEMENT

THIS AGREEMENT made

Between: HER MAJESTY THE QUEEN IN RIGHT OF CANADA, as represented by the
         Minister of Industry (hereinafter referred to as the "Minister")

And:     MARCH NETWORKS CORPORATION, a corporation duly incorporated under the
         laws of Canada, having its head office located at Ottawa, Ontario
         (hereinafter referred to as "a PROPONENT" or "MARCH NETWORKS").

And:     MITEL NETWORKS CORPORATION, a corporation duly incorporated under the
         laws of Canada, having its head office located at Ottawa, Ontario
         (hereinafter referred to as "a PROPONENT" or "MITEL NETWORKS").

And      MITEL KNOWLEDGE CORPORATION
         (hereinafter referred to as "a PROPONENT" or "MITEL KNOWLEDGE")

Collectively referred to as the PROPONENTS.

WHEREAS:

1.   The Minister and the Proponents entered into a Contribution Agreement dated
     the 10th day of October, 2002 pursuant to the Technology Partnerships
     Canada Program (the "Contribution Agreement"); and

2.   The Contribution Agreement was amended by letter dated March 27, 2003
     entitled Amendment Number 1; and

3.   Amendment Number 2 executed on April 27, 2004 further amended the
     Contribution Agreement, and

4.   Mitel Knowledge has pursuant to subsection 211 (4) of the Canada Business
     Corporations Act provided a Statement of Intent to Dissolve Mitel Knowledge

(CANADA LOGO)                                                          (GRAPHIC)

<PAGE>

                                        2

     Corporation to the Director under this Act. This Amendment Agreement is
     contingent upon the receipt by Mitel Knowledge of a Certificate of intent
     to dissolve pursuant to subsection 211(5) and section 262 of the Canada
     Business Corporations Act and remittance of same to the Minister as
     evidence that it has been dissolved.

5.   Mitel Knowledge has requested and the Minister has agreed following
     completion of an extensive case review to delete Mitel Knowledge as a
     Proponent to this Contribution Agreement pending receipt of the certificate
     of dissolution. Therefore, in consideration of their respective obligations
     set out in the Contribution Agreement the Minister and the Proponents now
     wish to further amend the Contribution Agreement.

THEREFORE, the Parties agree as follows:

1.   The above preamble is part of this Amendment Agreement (the "Agreement").

2.   Unless the context dictates otherwise, words and phrases defined in the
     Contribution Agreement have the same meaning in this Agreement

3.   PAGE 1 delete:

     "And: MITEL KNOWLEDGE CORPORATION, a corporation duly incorporated under
           the laws of Canada, having its head office located at Ottawa, Ontario
           (hereinafter referred to as "a PROPONENT" or "MITEL KNOWLEDGE")."

4.   ARTICLE 4.3 delete and replace with the following:

     4.3  Unless the Minister agrees otherwise in writing, and subject to the
          overall limit stipulated in section 4.1 above, the amount of the
          Contribution will not exceed the following amounts in the relevant
          Fiscal Years of the Project as follows:

                "2002/03:             $29,577,660
                 2003/04:             $15,312,078
                 2004/05:             $15,110,262"

     The Minister will consider any request to reprofile these funds, but the
     Minister will have no obligation to pay any greater amount in any of the
     said Fiscal Years except to the extent that such reprofiling will have been
     agreed to by the Minister.

<PAGE>

                                        3

4.   ARTICLE 7.2 delete address for Mitel Knowledge Corporation

     "Jose Madeiros"
      Chief financial Officer
      Mitel Knowledge Corporation
      555 Legged drive-Tower B
      Suite 534
      Ottawa, Ontario K2K 2X3"

6.    ARTICLE 8.15 delete in its entirety.

All provisions of the Contribution Agreement remain in full force and effect,
except as modified by this Amendment Agreement which will enter into force upon
receipt by the Minister of the Certificate of Dissolution issued by the
Director of Corporations to Mitel Knowledge.
<PAGE>

                                        4

IN WITNESS WHEREOF the parties hereto have executed this Amendment Agreement
through duly authorized representatives.

HER MAJESTY THE QUEEN IN RIGHT
OF CANADA, as represented by the Minister of Industry

Per: /s/ Denise Guevremont              Sept 9, 2004
     --------------------------------   Date
     Technology Partnerships Canada

Denise Guevremont, Director, Enabling Technologies Directorate

MARCH NETWORKS CORPORATION

Per: /s/ Peter Strom                    Sept 14, 04
     --------------------------------   Date
     Peter Strom President & CEO
     Name & Title

MITEL NETWORKS CORPORATION

Per: /s/ DON SMITH                      Sept 16, 04
     --------------------------------   Date
     DON SMITH CEO
     Name & Title

MITEL KNOWLEDGE CORPORATION

Per: /s/ JOSE MEDEIROS                  Sept 10, 2004
     --------------------------------   Date
     JOSE MEDEIROS CFO
     Name & Title

<PAGE>

(TECHNOLOGY PARTNERSHIPS CANADA LOGO)           PARTENARIAT TECHNOLOGIQUE CANADA

An Agency of Industry Canada                    Un organisme d'Industrie Canada

                                                      TPC PROJECT NO. 720-481443
                                                                  AMENDMENT NO.4

                         TECHNOLOGY PARTNERSHIPS CANADA

                               AMENDMENT AGREEMENT

THIS AGREEMENT MADE

Between: HER MAJESTY THE QUEEN IN RIGHT OF CANADA,
         as represented by the Minister of Industry
         (hereinafter referred to as the "Minister")

And:     MARCH NETWORKS CORPORATION, a corporation duly incorporated under the
         laws of Canada, having its head office located at Ottawa, Ontario
         (hereinafter referred to as "the Proponent" or "March Networks").

And:     MITEL NETWORKS CORPORATION, a corporation duly incorporated under
         the laws of Canada, having its head office located at Ottawa,
         Ontario (hereinafter referred to as "the Proponent" or "Mitel
         Networks").

And:     MARCH HEALTHCARE CORPORATION, a corporation duly incorporated under
         the laws of Canada, having its head office located at Ottawa, Ontario
         (hereinafter referred to as "the Proponent" or "March Healthcare").

         Collectively referred to as the PROPONENTS, and acting herein as
         joint and several.

INTRODUCTION

1.   The Minister, March Networks, Mitel Networks and Mitel Knowledge
     Corporation entered into a Contribution Agreement dated the 10th day of
     October, 2002 under the Technology Partnerships Canada Program (the
     "Contribution Agreement"); and

2.   The Contribution Agreement was amended by letter dated March 27, 2003
     entitled Amendment Number 1; and

3.   Amendment Number 2 executed on April 27, 2004 further amended the
     Contribution Agreement, and

4.   Amendment Number 3 executed on September 9, 2004 further amended the
     Contribution

(CANADA LOGO)                                                          (GRAPHIC)

<PAGE>

                                        2

     Agreement, and

5.   March Networks has requested and the Minister has agreed to insert March
     Healthcare as a Proponent, to this Contribution Agreement.

IN CONSIDERATION OF THEIR RESPECTIVE OBLIGATIONS SET OUT IN THE CONTRIBUTION
AGREEMENT, THE PARTIES AGREE TO AMEND THE CONTRIBUTION AGREEMENT AS FOLLOWS:

1.   At PAGE 1, insert:

     "And: MARCH HEALTHCARE CORPORATION, a corporation duly incorporated under
          the laws of Canada, having its head office located at Ottawa, Ontario
          (hereinafter referred to as "the Proponent" or "March Healthcare")."

2.   At ARTICLE 7.2, insert:

     Christine Cimaglia,
     Chief Operating Officer
     March Healthcare Corporation
     555 Legget Drive - Tower B
     Ottawa, Ontario K2K 2X3

     Fax: (613) 591-7337

3.   At Page 6, insert new ARTICLE 8.3.4

     "The Minister consents to the transfer of all Intellectual Property related
     to the March Networks tele-health solution be transferred to March
     Healthcare, effective as of the effective date of this Amendment Agreement
     No. 4 since March Healthcare is now one of the Proponents under this
     Agreement. The parties agree that March Healthcare will be responsible for
     its compliance with the terms and conditions of the Contribution Agreement
     for that portion of the Project that relates to the tele-health solution."

ALL PROVISIONS OF THE CONTRIBUTION AGREEMENT REMAIN IN FULL FORCE AND EFFECT,
EXCEPT AS MODIFIED BY THIS AMENDMENT AGREEMENT.

<PAGE>

                                       3

IN WITNESS WHEREOF the parties hereto have executed this Amendment Agreement
through duly authorized representatives.

HER MAJESTY THE QUEEN IN RIGHT
OF CANADA, as represented by the Minister of Industry

Per: /s/ Kash Ram                                2005-06-15
     -----------------------------------------   Date
     Technology Partnerships Canada

     KASH RAM, DIRECTOR, ENABLING TECHNOLOGIES
     Name & Title

MARCH NETWORKS CORPORATION

Per: /s/ Ken Taylor
     -----------------------------------------   2005-06-23
     KEN TAYLOR, CFO                             Date
     Name & Title

MITEL NETWORKS CORPORATION

Per: /s/ Don Smith
     -----------------------------------------   27 JUNE 05
     DON SMITH, CEO                              Date
     Name & Title

MARCH HEALTHCARE CORPORATION

Per: /s/ Christine Cimaglia
     -----------------------------------------   June 20/05
     CHRISTINE CIMAGLIA, COO                     Date
     Name & Title

<PAGE>

(TECHNOLOGY PARTNERSHIPS CANADA LOGO)           PARTENARIAT TECHNOLOGIQUE CANADA

An Agency of Industry Canada                    Un organisme d'Industrie Canada

                                                      TPC PROJECT NO. 720-481443
                                                                 AMENDMENT NO. 5

                         TECHNOLOGY PARTNERSHIPS CANADA

                               AMENDMENT AGREEMENT

THIS AGREEMENT MADE

Between: HER MAJESTY THE QUEEN IN RIGHT OF CANADA, as represented by the
         Minister of Industry (hereinafter referred to as the "Minister")

And:     MARCH NETWORKS CORPORATION, a corporation duly incorporated under the
         laws of Canada, having its head office located at Ottawa, Ontario
         (hereinafter referred to as "the Proponent" or "March Networks").

And:     MITEL NETWORKS CORPORATION, a corporation duly incorporated under the
         laws of Canada, having its head office located at Ottawa, Ontario
         (hereinafter referred to as "the Proponent" or "Mitel Networks").

And:     MARCH HEALTHCARE CORPORATION, a corporation duly incorporated under
         the laws of Canada, having its head office located at Ottawa, Ontario
         (hereinafter referred to as "the Proponent" or "March Healthcare").

         Collectively referred to as the PROPONENTS, and acting herein as
         joint and several.

INTRODUCTION

1.   The Minister, March Networks, Mitel Networks and Mitel Knowledge
     Corporation entered into a Contribution Agreement dated the 10th day of
     October, 2002 under the Technology Partnerships Canada Program (the
     "Contribution Agreement"); and

2.   The Contribution Agreement was amended by letter dated March 27, 2003
     entitled Amendment Number 1; and

3.   Amendment Number 2 executed on April 27, 2004 further amended the
     Contribution Agreement, and

(CANADA LOGO)                                                          (GRAPHIC)

<PAGE>

                                       2

4.   Amendment Number 3 executed on September 9, 2004 further amended the
     Contribution Agreement, and

5.   Amendment Number 4 executed on June 27, 2005 further amended the
     Contribution Agreement, and

6.   The Minister and the Proponent now wish to amend the Contribution
     Agreement.

IN CONSIDERATION OF THEIR RESPECTIVE OBLIGATIONS SET OUT IN THE CONTRIBUTION
AGREEMENT, THE PARTIES AGREE TO AMEND THE CONTRIBUTION AGREEMENT AS FOLLOWS:

1.   At Article 8, entitled "Special Conditions":

DELETE:

8.6  CONTRACTUAL BENEFITS TO CANADA

In the context of Schedule 4, Section B, Subparagraph 1b), the Minister hereby
consents that the Proponents may contract all of their manufacturing
requirements at arm's length outside of the Proponents companies. Furthermore,
the Minister hereby acknowledges that BreconRidge Manufacturing Solutions
Corporation may manufacture the resulting products outside Canada; any other
contract related to manufacturing to be carried on out of Canada shall require
the prior written consent of the Minister.

AND SUBSTITUTE WITH THE FOLLOWING:

8.6  CONTRACTUAL BENEFITS TO CANADA

In the context of Schedule 4, Section B, Subparagraph 1b), the Minister hereby
consents as follows:

     i)    that the Proponents may contract all of their manufacturing
           requirements at arm's length outside of the Proponents companies;

     ii)   that BrenconRidge Manufacturing Solutions Corporation may manufacture
           the resulting products outside of Canada;

     iii)  that the Proponents may manufacture any and all of their resulting
           IP-based products outside of Canada based on sound business, market
           and competitive considerations including pricing and cost
           competitiveness, profitability, local content regulations, and other
           factors which may vary with time. The Proponents nevertheless agree
           to make reasonable efforts to produce these products in Canada where
           these considerations permit them; and,

     iv)   that the Proponents may license Intellectual Property outside of
           Canada for the purpose of manufacturing their IP-based products
           developed under the Project.

Any other contract related to manufacturing to be carried on out of Canada shall
require the prior written consent of the Minister.

<PAGE>

                                        3

ALL PROVISIONS OF THE CONTRIBUTION AGREEMENT REMAIN IN FULL FORCE AND EFFECT,
EXCEPT AS MODIFIED BY THIS AMENDMENT AGREEMENT.

IN WITNESS WHEREOF the parties hereto have executed this Amendment Agreement
through duly authorized representatives.

HER MAJESTY THE QUEEN IN RIGHT
OF CANADA, as represented by the Minister of Industry

Per: /s/ Linda Dunn                                   Sept. 26/05
     ----------------------------------------------   Date
     Technology Partnerships Canada

     Linda Dunn, A/Director - Enabling Technologies

MARCH NETWORKS CORPORATION

Per: /s/ Peter Strom                                  Oct 1, 05
     ----------------------------------------------   Date
     Peter Strom
     President & CEO
     Name & Title

MITEL NETWORKS CORPORATION

Per: /s/ Steve Spooner                                9/30/05
     ----------------------------------------------   Date
     Steve Spooner
     CFO
     Name & Title

<PAGE>

                                        4

MARCH HEALTHCARE CORPORATION

Per: /s/ CHRISTINE CIMAGLIA                           3 OCT 05
     ----------------------------------------------   Date
     CHRISTINE CIMAGLIA, COO
     Name & Title

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