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 September 9, 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