Third Amendment to the Nortel Networks U.S. Deferred Compensation Plan

Exhibit 10.80

Third Amendment to the Nortel Networks

U.S. Deferred Compensation Plan

WHEREAS , Nortel Networks Limited (the “Company”) sponsors the Nortel Networks U.S. Deferred Compensation Plan (the “Plan”) and has reserved the right in Section 9.3. of the Plan to amend the Plan at any time in its sole discretion; and

WHEREAS , the Company has delegated to the Compensation and Human Resources Committee (the “CHRC”) of the Board of Directors of the Company the right to approve amendments to the Plan at any time in its sole discretion; and

WHEREAS, the CHRC desires to amend the provisions of the Plan concerning participation in the Plan for the 2009 Plan Year; and

NOW, THEREFORE, the Plan is hereby amended in the following respects, effective as of January 1, 2009:

Section 2.3 of the Plan is hereby amended in its entirety to read as follows:

“2.3 Cessation of Participation . Active participation in the Plan shall end when a Participant’s employment with all Employers that have adopted the Plan terminates for any reason or when the Board or the Committee determines, in its sole discretion, to remove such Par