EXHIBIT 99.1

JOINT FILING AGREEMENT

In accordance with Rule 13d-1(k) under the Securities Exchange Act of 1934, as amended, each of the persons named below agrees to the joint filing of a Statement on Schedule 13D (including amendments thereto) with respect to the common shares of Mitel Networks Corporation, and further agrees that this joint filing agreement be included as an exhibit to such filings provided that, as contemplated by Section 13d-1(k)(1)(ii), no person shall be 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.

Dated: August 27, 2007

MORGAN STANLEY

/s/ Dennine Bullard

Name: Dennine Bullard

Title: Authorized Signatory

MORGAN STANLEY PRINCIPAL INVESTMENTS, INC.

/s/ David Bersh

Name: David Bersh

Title: Vice President