Exhibit II

to

Schedule 13G

Joint Filing Agreement

The undersigned persons agree and consent to the joint filing on their behalf of this Schedule 13G dated August 10, 2011 in connection with their beneficial ownership of Acme Packet Inc. Each of Columbia Select Large Cap Growth Fund and Columbia Management Investment Advisers, LLC authorizes Ameriprise Financial, Inc. to execute the Schedule 13G to which this Exhibit is attached and make any necessary amendments thereto.

Ameriprise Financial, Inc.
By:	/s/ Wade M. Voigt Wade M. Voigt
	Director — Fund Administration
Columbia Management Investment Advisers, LLC
	By: /s/ Amy Johnson Amy Johnson
	Chief Operating Officer
Columbia Funds Series Trust I,
on behalf of its series Columbia Select Large Cap Growth Fund
By:	/s/ Scott R. Plummer Scott R. Plummer
	General Counsel

August 10, 2011

Peter Minihane
Acme Packet Inc.
100 Crosby Drive
Bedford, MA 01730

RE: Schedule 13G

Enclosed pursuant to Rule 13d-1(b) under the Securities Exchange Act of 1934 is a report on Schedule 13G reporting beneficial ownership at July 31, 2011 by Ameriprise Financial, Inc. and its related entities in Common Stock of Acme Packet Inc.

Sincerely,

Wade M. Voigt
Director — Fund Administration

Enclosure