SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D/A

Under the Securities Exchange Act of 1934

(Amendment No. 5)

Mitel Networks Corporation

(Name of Company)

Common Shares, No Par Value

(Title of Class of Securities)

60671Q104

(CUSIP Number)

Paul Chiarelli

President

Wesley Clover International Corporation

390 March Road, Suite 110,

Ottawa, Ontario K2K 0G7

(613) 271-6305

(Name, Address and Telephone Number of Persons Authorized to Receive Notices and Communications)

With a Copy to:

James Lurie, Esq.

Osler, Hoskin & Harcourt LLP

620 8^th Avenue, 36^th Floor

New York, New York 10018

(212) 867-5800

November 11, 2013

(Date of Event which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition which is the subject of this Schedule 13D, and is filing this schedule because of §§240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.  ¨

Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See §240.13d-7 for other parties to whom copies are to be sent.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (the “Exchange Act”) or otherwise subject to the liabilities of that section of the Exchange Act but shall be subject to all other provisions of the Exchange Act (however, see the Notes).

SCHEDULE 13D

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SCHEDULE 13D

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SCHEDULE 13D

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SCHEDULE 13D

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This Amendment No. 5 to Schedule 13D (this “Amendment No. 5”) is being filed on behalf of Dr. Terence H. Matthews (“Dr. Matthews”), Kanata Research Park Corporation (“Kanata”), Wesley Clover International Corporation (“WCIC”) and 4293711 Canada Inc.(“4293711 Canada” and, together with Dr. Matthews, WCIC and Kanata, the “Reporting Persons”), relating to the common shares, without par value (the “Common Shares”) of Mitel Networks Corporation, a corporation existing under the laws of Canada (the “Company”). This Amendment No. 5 amends and supplements the initial statement on Schedule 13D (the “Original 13D”), filed on July 14, 2005 by Dr. Matthews, Wesley Clover Corporation (“WCC”) and Celtic Jet Tech Limited (“Celtic”), as amended and supplemented by Amendment No. 1 on Schedule 13D, filed on May 5, 2006, Amendment No. 2 on Schedule 13D, filed on September 27, 2006, Amendment No. 3, which was inadvertently labeled Amendment No. 2, on Schedule 13D, filed on September 28, 2007, each of which was filed by Dr. Matthews, WCC and Celtic and Amendment No. 4, on Schedule 13D, filed on July 7, 2010 by Dr. Matthews, WCC, WCIC and 4293711 Canada.

WCC, formerly a wholly owned subsidiary of WCIC, a holder of Common Shares of the Company and a reporting person for purposes of this Schedule 13D, was amalgamated with Kanata pursuant to a Certificate of Amalgamation filed with Industry Canada on January 1, 2013 whereby WCC was the surviving entity and WCC was renamed Kanata. As a result of the amalgamation, the

Common Shares previously held by WCC are now beneficially owned by Kanata.

ITEM 2. IDENTITY AND BACKGROUND

Item 2 is hereby amended and supplemented as follows:

(a), (b), (c) and (f). Dr. Matthews’ business address is 390 March Road, Suite 110, Ottawa, Ontario K2K 0G7. Dr. Matthews is Chairman of the Company. Dr. Matthews is a citizen of Canada.

Kanata, a corporation existing under the laws of Canada, is primarily engaged in real estate development and real estate management. Kanata’s principal business and principal office address is 555 Legget Drive, Suite 206, Ottawa, Ontario K2K 2X3. The name, citizenship, present principal occupation or employment and business address of each director and executive officer of Kanata is set forth below:

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WCIC, a corporation existing under the laws of Canada, is a holding company that is primarily engaged in the business of investing in securities. WCIC’s principal business and principal office address is 390 March Road, Suite 110, Ottawa, Ontario, Canada, K2K 0G7. The name, citizenship, present principal occupation or employment and business address of each director and executive officer of WCIC is set forth below:

4293711 Canada, a corporation existing under the laws of Canada, is the holding company for investments controlled by Dr. Matthews. 4293711 Canada’s principal business and principal office address is 390 March Road, Suite 110, Ottawa, Ontario K2K 0G7. The name, citizenship, present principal occupation or employment and business address of each director and executive officer of 4293711 Canada is set forth below:

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Dr. Matthews owns 100% of the outstanding voting shares of 4293711 Canada which in turn owns 99.9% of the outstanding voting shares of WCIC. WCIC owns 100% of the outstanding voting shares of Kanata.

(d) None of the Reporting Persons nor any of their directors or executive officers has, during the last five years, been convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors).

(e) None of the Reporting Persons nor any of their directors or executive officers has, during the last five years, been a party to a civil proceeding of a judicial or administrative body of competent jurisdiction and as a result of such proceeding was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to, federal or state securities laws or finding any violation with respect to such laws.

Pursuant to Rule 13d-3 under the Securities Exchange Act of 1934, as amended (the “Exchange Act”), by reason of the relationships among the Reporting Persons, WCIC, 4293711 Canada and Dr. Matthews may be deemed the beneficial owner of all of the Common Shares beneficially owned by Kanata. Dr. Matthews, WCIC, Kanata and 4293711 Canada may be regarded as a group for purposes of Rule 13d-5 under the Exchange Act.

ITEM 4. PURPOSE OF TRANSACTION.

Item 4 is hereby amended and supplemented as follows:

The Reporting Persons are continuously evaluating the business and prospects of the Company, and their present and future interests in, and intentions with respect to, the Company.

Although the Reporting Persons do not have any specific plan or proposal to acquire or dispose of any securities of the Company, the Reporting Persons may from time to time formulate other plans or proposals that relate to, might result in, or have the purpose or effect of changing or influencing control of the Company, or that relate to or would result in any of the events enumerated in paragraphs (a) through (j) of Item 4 of Schedule 13D. Such plans or proposals will depend upon the Reporting Persons ongoing evaluation of their investment in the Company, prevailing market conditions, developments affecting the Company, other opportunities, liquidity requirements of the Reporting Persons, tax considerations and/or other considerations. Also, the Reporting Persons or their representatives may engage in communications with one or more directors, officers, representatives or shareholders of the Company and/or third party advisors or financing sources regarding the Company, including but not limited to, the Company’s operations, plans or prospects. The Reporting Persons may acquire additional securities of the Company as they deem appropriate. Alternatively, the Reporting Persons may dispose of some or all of the securities of the Company in privately negotiated transactions or otherwise. The Reporting Persons may discuss ideas that, if effected may result in any of the events enumerated in paragraphs (a) through (j) of Item 4 of Schedule 13D, including the acquisition by other persons of shares of the Company, an extraordinary corporate transaction involving the Company, and/or changes in the board of directors or management of the Company. Except to the extent the foregoing may be deemed a plan or proposal, the Reporting Persons do not have any plans or proposals which relate to, or could result in, any of the matters enumerated in paragraphs (a) through (j) of Item 4 of Schedule 13D.

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ITEM 5. INTEREST IN SECURITIES OF THE COMPANY.

Item 5 is hereby amended and supplemented as follows:

The following disclosure is based on 53,784,184 Common Shares of the Company outstanding, as of August 27, 2013, as reported in the Company’s Form 10-Q for the period ended July 31, 2013.

(a) As of the date hereof, the Reporting Persons beneficially own the aggregate number and percentage of outstanding Common Shares set forth below:

(b) Dr. Matthews

Dr. Matthews has the sole power to vote or direct the vote and sole power to dispose or direct the disposition of 316,162 Common Shares issuable upon exercise of options that are exercisable within 60 days.

Dr. Matthews has shared power to vote or direct the vote and shared power to dispose or direct the disposition of 12,080,610 Common Shares directly owned by WCC.

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Kanata

Kanata has shared power to vote or direct the vote and shared power to dispose or direct the disposition of 12,080,610 Common Shares.

Kanata does not have the sole power to vote or direct the vote or sole power to dispose or direct the disposition of any Common Shares.

4293711 Canada

4293711 Canada has shared power to vote or direct the vote and shared power to dispose or direct the disposition of 12,080,610 Common Shares.

4293711 Canada does not have the sole power to vote or direct the vote or sole power to dispose or direct the disposition of any Common Shares.

WCIC

WCIC has shared power to vote or direct the vote and shared power to dispose or direct the disposition of 12,080,610 Common Shares.

WCIC does not have the sole power to vote or direct the vote or sole power to dispose or direct the disposition of any Common Shares.

To the knowledge of the Reporting Persons, none of the directors or executive officers of Kanata, WCIC and 4293711 Canada beneficially own any Common Shares of the Company, except for Dr. Matthews as reported in this Amendment No. 5 and Paul Chiarelli who owns 1,067 Common Shares.

(c) During the last 60 days there were no transactions in the Common Shares affected by the Reporting Persons, nor, to the knowledge of the Reporting Persons, any of their directors or executive officers.

(d) Not applicable.

(e) WCC ceased to be the beneficial owner of more than 5% of the Common Shares when it was amalgamated into Kanata on January 1, 2013. As a result of the amalgamation, the Common Shares previously held by WCC are now beneficially owned by Kanata.

ITEM 6. CONTRACTS, ARRANGEMENTS, UNDERSTANDINGS OR RELATIONSHIPS WITH RESPECT TO SECURITIES OF THE COMPANY.

Item 6 is hereby amended and supplemented as follows:

Pursuant to Rule 13d-1(k) under the Exchange Act, the Reporting Persons have entered into an agreement, attached hereto as Exhibit 99.1, with respect to the joint filing of this statement.

On November 10, 2013, the Company and Aastra Technologies Limited (“Aastra”) entered into an arrangement agreement (the “Arrangement Agreement”) setting out the terms under which the

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arrangement (the “Arrangement”) will be undertaken. In connection with the Arrangement, Dr. Matthews and Kanata, and certain other shareholders of the Company, all of whom together collectively control approximately 60% of the Common Shares of the Company, have entered into voting support agreements with the Company and Aastra, dated November 10, 2013 (each a “Voting Support Agreement”). Dr. Matthews and Kanata entered into a Voting Support Agreement (the “Matthews Group VSA”) whereby each of them has agreed in their capacity as a shareholder of the Company to: (i) vote all of the Subject Shares (as defined in the Matthews Group VSA) held by them in favor of the approval, consent, ratification and adoption of the Arrangement Agreement and the transactions contemplated by the Arrangement Agreement, subject to certain customary exceptions; and (ii) not to sell, transfer, gift, assign, convey, pledge, hypothecate, encumber, option, grant a security interest in or otherwise dispose of any right or interest in any Subject Shares, subject to certain exceptions. Additionally, Dr. Matthews and Kanata have agreed for a period of 180 days following the effective date of the consummation of the transactions contemplated by the Arrangement Agreement not to sell, hypothecate, pledge, grant any option to purchase or otherwise dispose of or agree to dispose of, directly or indirectly, 10,872,549 Subject Shares, subject to certain exceptions. The Reporting Persons have not received any monetary consideration as a result of Dr. Matthews or Kanata entering into the Matthews Group VSA and have not purchased any securities of the Company in connection with the transactions described herein.

The foregoing description of the Matthews Group VSA does not purport to be complete and is qualified in its entirety by reference to the Matthews Group VSA, a copy of which is attached hereto as Exhibit 99.2, and which is incorporated herein by reference. This Amendment No. 5 does not purport to amend, qualify or in any way modify the Matthews Group VSA.

ITEM 7. MATERIAL TO BE FILED AS EXHIBITS.

Item 7 is hereby amended and supplemented by adding the following exhibits:

99.1 Joint Filing Agreement, dated as of November 20, 2013, among Dr. Terence H. Matthews, 4293711 Canada Inc., Wesley Clover International Corporation and Kanata Research Park Corporation.

99.2 Voting Support Agreement dated November 10, 2013 among Aastra Technologies Limited, Mitel Networks Corporation, Dr. Terence H. Matthews and Kanata Research Park Corporation.

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SIGNATURES

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Dated: November 20, 2013

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Exhibit 99.1

JOINT FILING AGREEMENT

This confirms the agreement by and among the undersigned that the Statement on Amendment No. 5 to Schedule 13D (the “Statement”) filed on or about this date with respect to the beneficial ownership by the undersigned of the common shares, no par value, of Mitel Networks Corporation, is being filed on behalf of each of the undersigned.

Each of the undersigned hereby acknowledges that pursuant to Rule 13d-1(k) promulgated under the Securities Exchange Act of 1934, as amended, each person on whose behalf the Statement is being filed is individually eligible to use the schedule on which the information is filed, each person on whose behalf the Statement is filed is responsible for the timely filing of such Statement and any amendments thereto and for the completeness and accuracy of the information concerning such person contained therein, and that such person is not responsible for the completeness or accuracy of the information concerning the other persons making the filing, unless such person knows or has reason to believe that such information is inaccurate.

Each of the undersigned agrees that Wesley Clover International Corporation shall be authorized to receive notices and communications on behalf of the undersigned relating to the Statement.

This Agreement may be executed in two or more counterparts, each of which, taken together, shall constitute one and the same instrument.

Dated: November 20, 2013

Exhibit 99.2

VOTING SUPPORT AGREEMENT

THIS AGREEMENT is made as of November 10, 2013

BETWEEN:

AASTRA TECHNOLOGIES LIMITED, a corporation existing under the laws of Canada (“Aastra”)

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MITEL NETWORKS CORPORATION, a corporation existing under the laws of Canada (“Mitel”)

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DR. TERENCE H. MATTHEWS, an individual resident in the City of Ottawa (“Dr. Matthews”)

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KANATA RESEARCH PARK CORPORATION, a corporation existing under the laws of Canada (the “Securityholder”)

RECITALS:

NOW THEREFORE, in consideration of the mutual covenants in this Agreement and for other good and valuable consideration (the receipt and sufficiency of which are hereby acknowledged) the parties hereto agree as follows:

ARTICLE 1

INTERPRETATION

Capitalized terms used herein and not otherwise defined have the meanings ascribed thereto in the Arrangement Agreement. In this Agreement, including the recitals:

“Arrangement Agreement” means the arrangement agreement dated as of the date hereof between Aastra and Mitel, as the same may be amended in accordance with its terms;

“Business Day” means any day, other than a Saturday, a Sunday or a statutory or civic holiday in Toronto, Ontario;

“Contracts” means contracts, licences, leases, agreements, obligations, promises, undertakings, understandings, arrangements, documents, commitments, entitlements or engagements to which the Securityholder is a party or by which it is bound or under which the Securityholder has, or will have, any liability or contingent liability (in each case, whether written or oral, express or implied), and includes any quotations, orders, proposals or tenders which remain open for acceptance and warranties and guarantees;

“Convertible Securities” has the meaning ascribed thereto in Section 2.1(b);

“Expiry Time” has the meaning ascribed thereto in Section 3.1(a);

“Locked-Up Securities” has the meaning ascribed thereto in Section 3.1(c);

“Notice” has the meaning ascribed thereto in Section 4.7;

“Subject Shares” means all Mitel Shares beneficially owned or controlled, directly or indirectly, by the Securityholder and its Affiliates as at the date hereof, and shall further include any Mitel Shares acquired or over which control is acquired by the Securityholder after the date hereof; and

“Transfer” has the meaning ascribed thereto in Section 3.1(a).

In this Agreement, words importing the singular number include the plural and vice versa and words importing gender include the masculine, feminine and neuter genders.

Unless otherwise expressly stated, all references to currency herein shall be deemed to be references to Canadian currency.

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The division of this Agreement into Articles, Sections and Schedules and the insertion of the recitals and headings are for convenience of reference only and shall not affect the construction or interpretation of this Agreement and, unless otherwise stated, all references in this Agreement or in the Schedules hereto to Articles, Sections and Schedules refer to Articles, Sections and Schedules of and to this Agreement or of the Schedules in which such reference is made, as applicable.

In the event that any date on which any action is required to be taken hereunder by any of the parties is not a Business Day, such action shall be required to be taken on the next succeeding day which is a Business Day.

This Agreement shall be governed, including as to validity, interpretation and effect, by the laws of the Province of Ontario and the laws of Canada applicable therein, and shall be construed and treated in all respects as an Ontario contract. Each of the parties hereby irrevocably attorns to the non-exclusive jurisdiction of the Courts of the Province of Ontario in respect of all matters arising under and in relation to this Agreement.

The Schedules attached hereto and described below shall, for all purposes hereof, form an integral part of this Agreement.

Schedule A – Subject Shares

Schedule B – Form of Written Consent

ARTICLE 2

REPRESENTATIONS AND WARRANTIES

The Securityholder represents and warrants to Aastra and Mitel (and acknowledges that Aastra and Mitel are relying on these representations and warranties in completing the transactions contemplated hereby and by the Arrangement Agreement) the matters set out below:

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Aastra represents and warrants to the Securityholder (and acknowledges that the Securityholder is relying on these representations and warranties in completing the transactions contemplated hereby and by the Arrangement Agreement) that Aastra is a corporation duly incorporated and validly existing under the laws of the Canada and has all necessary corporate power, authority and capacity to enter into this Agreement and to carry out its obligations under this Agreement. The execution and delivery of this Agreement and the consummation of the transactions contemplated by this Agreement have been duly authorized by all necessary corporate action on the part of Aastra. This Agreement constitutes a valid and binding obligation of Aastra enforceable against it in accordance with its terms, subject to bankruptcy, insolvency and other Laws affecting the enforcement of creditors’ rights generally and subject to the qualification that equitable remedies may only be granted in the discretion of a court of competent jurisdiction.

Mitel represents and warrants to the Securityholder (and acknowledges that the Securityholder is relying on these representations and warranties in completing the transactions contemplated hereby and by the Arrangement Agreement) that Mitel is a corporation duly incorporated and validly existing under the laws of the Canada and has all necessary corporate power, authority and capacity to enter into this Agreement and to carry out its obligations under this Agreement.

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The execution and delivery of this Agreement and the consummation of the transactions contemplated by this Agreement have been duly authorized by all necessary corporate action on the part of Mitel. This Agreement constitutes a valid and binding obligation of Mitel enforceable against it in accordance with its terms, subject to bankruptcy, insolvency and other Laws affecting the enforcement of creditors’ rights generally and subject to the qualification that equitable remedies may only be granted in the discretion of a court of competent jurisdiction.

ARTICLE 3

COVENANTS

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In connection with the foregoing, subject to this Section 3.1(b), the Securityholder hereby irrevocably and unconditionally agrees, upon the request of Mitel or Aastra, to (A) deposit an irrevocable proxy, duly completed and executed in respect of all of the Subject Shares at least 10 days prior to any meeting of the holders of Mitel Shares to consider any of the matters identified in paragraph (i) of this Section 3.1(b), voting all such Subject Shares in favour of the applicable matter(s), and (B) deliver to Mitel or Aastra, as applicable, an irrevocable written consent, duly completed and executed in respect of all of the Subject Shares within 10 days of any request by Mitel or Aastra to provide such written consent in support of any of the matters identified in paragraph (i) of this Section 3.1(b) (including, without limitation, a consent addressed to the TSX and NASDAQ confirming that such holder is in favour of the Arrangement and the issuance of the Consideration Shares and Option Shares, which consent shall be substantially in the form attached as Schedule B hereto, with such changes as may be required by the TSX or NASDAQ). The Securityholder hereby irrevocably and unconditionally agrees that neither it nor any person on its behalf will take any action to withdraw, amend or invalidate any proxy or consent deposited by the Securityholder pursuant to this Agreement notwithstanding any statutory or other rights which the Securityholder might have unless this Agreement is terminated in accordance with Section 4.1.

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The Securityholder hereby authorizes Mitel and its transfer agent, during the Lock-Up Period, to decline the transfer of, or to note stop transfer restrictions on the stock register and other records relating to the Locked-Up Securities of which the Securityholder is the registered holder, and, with respect to Locked-Up Securities of which the Securityholder is the beneficial owner but not the registered holder, the Securityholder hereby agrees to cause such registered holder to authorize Mitel and its transfer agent, during the Lock-Up Period, to decline the transfer of or to note stop transfer restrictions on the stock register and other records relating to such Locked-Up Securities. Notwithstanding the foregoing, if any other party is released, in full or in part, from the lock-up restrictions of any similar voting support agreement related to the transactions contemplated by the Arrangement Agreement, then the Securityholder shall be released in the same manner from the restrictions of this Agreement (i.e., in the case where shares of such individual or entity are released from lock-up restrictions, the same percentage of shares held by the Securityholder shall be released from the restrictions of this Agreement on the same terms).

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ARTICLE 4

GENERAL

This Agreement shall terminate and be of no further force or effect only upon the earliest of:

Any date, time or period referred to in this Agreement shall be of the essence, except to the extent to which the Securityholder, Dr. Matthews, Aastra and Mitel agree in writing to vary any date, time or period, in which event the varied date, time or period shall be of the essence.

The parties agree that irreparable harm will occur for which money damages will not be an adequate remedy at Law in the event that any of the provisions of this Agreement are not performed by the Securityholder in accordance with their terms or are otherwise breached. It is accordingly agreed that Aastra and Mitel shall be entitled to an injunction or injunctions and other equitable relief to prevent breaches or threatened breaches of the provisions of this Agreement by the Securityholder and shall be entitled to obtain specific performance by the Securityholder of any such provisions. The Securityholder hereby agrees not to seek the posting of any security bond or other assurance in respect of such injunctive or other equitable relief. Such remedies will not be the exclusive remedies for any breach of this Agreement and will be in addition to all other remedies available at Law or equity.

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Aastra and Mitel acknowledge that the Securityholder is not making any agreement or understanding herein in any capacity other than in its capacity as securityholder of Mitel. Nothing herein shall restrict the Securityholder or Dr. Matthews from taking in good faith any actions necessary to discharge Dr Matthews’ fiduciary duties as a director or officer of Mitel.

Each party hereto agrees and confirms that any provision of this Agreement may be amended or waived if, and only if, such amendment or waiver is in writing and signed, in the case of an amendment, by the Securityholder, Dr. Matthews, Aastra and Mitel or in the case of a waiver, by the party against whom the waiver is to be effective and no failure or delay by any party in exercising any right, power or privilege hereunder shall operate as a waiver thereof nor shall any single or partial exercise thereof preclude any other or further exercise.

This Agreement constitutes the entire agreement among the parties with respect to the subject matter hereof and supersedes all prior agreements and understandings among the parties with respect thereto.

Any notice, consent or approval required or permitted to be given in connection with this Agreement (in this Section referred to as a “Notice”) shall be in writing and shall be sufficiently given if delivered (whether in person, by courier service or other personal method of delivery), or if transmitted by facsimile or e-mail:

Mitel Networks Corporation

350 Legget Drive

Kanata, ON, Canada K2K 2W7

with a copy (which shall not constitute notice) to:

Osler, Hoskin & Harcourt LLP

1 First Canadian Place, Suite 6600

Toronto, Ontario M5X 1B8

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Aastra Technologies Limited

155 Snow Boulevard

Concord, Ontario, Canada L4K 4N9

with a copy (which shall not constitute notice) to:

McCarthy Tétrault LLP

Suite 5300, TD Bank Tower

Box 48, 66 Wellington Street West

Toronto ON M5K 1E6

c/o Kanata Research Park Corporation

350 Leggett Drive

Kanata, ON K2K 2W7

Attn: Dr. T.H. Matthews, Paul Chiarelli and Christa Plumley

Fax: (613) 271-9810

Email: pchiarelli@wesleyclover.com; cplumley@wesleyclover.com

with a copy to (which shall not constitute notice):

Osler, Hoskin & Harcourt LLP

P.O. Box 50

1 First Canadian Place

100 King Street West

Toronto, ON M5X 1B8

Attention: J. Mark DesLauriers

Fax: (416) 862-6666

E-mail: mdeslauriers@osler.com

Any Notice delivered or transmitted to a party as provided above shall be deemed to have been given and received on the day it is delivered or transmitted, provided that it is delivered or transmitted on a Business Day prior to 5:00 p.m. local time in the place of delivery or receipt. If the Notice is delivered or transmitted after 5:00 p.m. local time or if the day is not a Business Day, then the Notice shall be deemed to have been given and received on the next Business Day.

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Either party hereto may, from time to time, change its address by giving Notice to the other parties in accordance with the provisions of this Section 4.7.

If, in any jurisdiction, any provision of this Agreement or its application to any party or circumstance is restricted, prohibited or unenforceable, such provision shall, as to such jurisdiction, be ineffective only to the extent of such restriction, prohibition or unenforceability without invalidating the remaining provisions of this Agreement and without affecting the validity or enforceability of such provision in any other jurisdiction or without affecting its application to other parties or circumstances. Upon such determination that any term or other provision is invalid, illegal or incapable of being enforced, the parties hereto shall negotiate in good faith to modify this Agreement so as to effect the original intent of the parties as closely as possible in a mutually acceptable manner in order that the terms of this Agreement remain as originally contemplated to the fullest extent possible.

The provisions of this Agreement shall be binding upon and enure to the benefit of the parties hereto and their respective successors, permitted assigns and legal personal representatives, provided that no party may assign, delegate or otherwise transfer any of its rights, interests or obligations under this Agreement without the prior written consent of the other parties hereto, except that Aastra may assign, delegate or otherwise transfer any of its rights, interests or obligations under this Agreement to an Affiliate without reducing its own obligations hereunder without the consent of the Securityholder.

Each party shall pay all costs and expenses (including the fees and disbursements of legal counsel and other advisers) it incurs in connection with the negotiation, preparation and execution of this Agreement and the transactions contemplated by this Agreement.

The Securityholder acknowledges that it has been afforded the opportunity to obtain independent legal advice and confirms by the execution of this Agreement that it has either done so or waived its right to do so in connection with the entering into of this Agreement.

The parties hereto shall, with reasonable diligence, do all things and provide all such reasonable assurances as may be required to consummate the transactions contemplated by this Agreement, and each party shall provide such further documents or instruments required by the other party as may be reasonably necessary or desirable to effect the purpose of this Agreement and carry out its provisions, whether before or after the Effective Time.

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This Agreement may be executed in one or more counterparts, each of which shall be deemed to be an original but all of which together shall constitute one and the same instrument. The parties shall be entitled to rely upon delivery of an executed facsimile or similar executed electronic copy of this Agreement, and such facsimile or similar executed electronic copy shall be legally effective to create a valid and binding agreement between the parties.

[Signature page follows.]

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IN WITNESS OF WHICH the parties have executed this Agreement.

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SCHEDULE “A”

A-1

SCHEDULE “B”

FORM OF WRITTEN CONSENT

(see attached)

WRITTEN CONSENT

WHEREAS Kanata Research Park Corporation (“Kanata”) beneficially owns 12,080,610 common shares of Mitel Networks Corporation (“Mitel”) as of the date hereof, representing voting ownership of approximately 22.4% of the outstanding Mitel common shares (“Mitel Shares”);

AND WHEREAS Arsenal Holdco I S.A.R.L. (“Arsenal I”) and Arsenal Holdco II S.A.R.L. (“Arsenal II”, and together with Arsenal I, “Arsenal”) collectively beneficially own 20,097,546 Mitel Shares as of the date hereof, representing voting ownership of approximately 37.3% of the outstanding Mitel Shares, and together with Kanata, 59.7% of the outstanding Mitel Shares;

AND WHEREAS on November 10, 2013, Mitel entered into an arrangement agreement with Aastra Technologies Limited (“Aastra”) pursuant to which Mitel has agreed to acquire all of the outstanding common shares of Aastra by way of an arrangement under the Canada Business Corporations Act (the “Arrangement”) for consideration consisting of cash and Mitel Shares;

AND WHEREAS Mitel expects to issue up to approximately — million Mitel Shares in connection with the Arrangement, representing approximately —% of the total number of outstanding Mitel Shares as of the date hereof, consisting of: (i) approximately — million Mitel Shares to be issued to Aastra shareholders; and (ii) up to approximately — Mitel Shares to be issued upon exercise of replacement options to be issued to holders of Aastra options in exchange for such options;

AND WHEREAS upon completion of the Arrangement: (i) Kanata will have voting ownership of approximately 12.8% of the outstanding Mitel Shares; (ii) Arsenal will have voting ownership of approximately 21.3% of the outstanding Mitel Shares; (iii) Mitel shareholders, other than Kanata and Arsenal, will hold approximately 22.9% of the outstanding Mitel Shares; and (iv) former Aastra shareholders will hold approximately 43% of the outstanding Mitel Shares;

AND WHEREAS each of Kanata, Arsenal I and Arsenal II acknowledge that the Arrangement will likely be completed during the first quarter of 2014 and, in any event, no later than March 14, 2014;

AND WHEREAS each of Kanata, Arsenal I and Arsenal II are familiar with the terms of the Arrangement;

AND WHEREAS as the number of Mitel Shares to be issued in connection with the Arrangement (the “Mitel Share Issuance”) exceeds 25% of the total number of outstanding Mitel Shares, the Mitel Share Issuance requires the approval of Mitel shareholders under section 611(c) of the TSX Company Manual;

AND WHEREAS as the Mitel Shares Issuance exceeds 20% of the total number of outstanding Mitel Shares, the Mitel Share Issuance requires the approval of Mitel shareholders under Rule 5635(a)(1)(A) of the NASDAQ Stock Market Rules (the “NASDAQ Rules”), absent the availability of an exemption therefrom;

AND WHEREAS this Notice is being submitted to the TSX under section 604(d) of the TSX Company Manual and under Rule 5635(e)(4) of the NASDAQ Rules as written evidence of the required shareholder approval of the Mitel Share Issuance;

NOW THEREFORE each of Kanata, Arsenal I and Arsenal II confirms that it is in favour of the Arrangement and irrevocably consents to the Mitel Share Issuance.

[The remainder of this page is left blank intentionally]

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DATED this     day of November, 2013.

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