Exhibit 99.1

Investor Relations Contact:		Media and Analyst Contact:
Brian Norris		Mike O’Malley
Acme Packet		Acme Packet
+1.781.328.4790		+1.781.869.2975
bnorris@acmepacket.com		momalley@acmepacket.com

Acme Packet Reports Results for Third Quarter of 2011

– Company Reaffirms 2011 Revenue and Earnings Estimates —

Bedford, Massachusetts — October 20, 2011 — Acme Packet, Inc. (NASDAQ: APKT), the leader in session delivery network solutions, today announced results for the third quarter ended September 30, 2011 and reaffirmed its business outlook for 2011.

Results for the Third Quarter of 2011

Total revenue in the third quarter of 2011 was $70.6 million, compared to $56.6 million in the third quarter of 2010 and $79.7 million in the second quarter of 2011. Net income in the third quarter of 2011 was $7.9 million, or $0.11 per share, compared to $10.5 million, or $0.15 per share, in the third quarter of 2010 and $14.0 million, or $0.20 per share, in the second quarter of 2011. Net income on a non-GAAP¹ basis in the third quarter of 2011 was $14.6 million, or $0.21 per share, compared to $13.7 million, or $0.20 per share, in the third quarter of 2010, and $20.4 million, or $0.29 per share, in the second quarter of 2011. All earnings per share results are on a fully diluted basis.

“The fundamentals of our business remain strong, and we remain well positioned to take advantage of the profound shift to Internet-based voice, video and unified communications,” said Andy Ory, President and CEO of Acme Packet, Inc. “We are excited about the new products and partnerships that we have launched to drive the next stage of our growth. We remain confident in our ability to execute on our full year business outlook.”

Company Reaffirms Business Outlook for 2011

The Company today reaffirmed its business outlook for 2011. The Company’s outlook is based on the current indications for its business, which may change at any time. A reconciliation of the Company’s

expected GAAP to non-GAAP¹ business outlook, and a statement as to the use of non-GAAP¹ financial measures, is included at the end of this press release. All earnings per share results are on a fully diluted basis.

Business Outlook for Year Ending December 31, 2011
Estimate		Issued October 20, 2011
Total revenue (in millions)		$	315-$320
Total revenue growth rate		Approximately 36%-38%
Non-GAAP1 EPS		$	1.14-$1.18
Non-GAAP1 EPS growth rate		Approximately 43%-48%
GAAP EPS		$	0.78-$0.82
GAAP EPS growth rate		Approximately 24%-30%
Diluted share count (in millions)			71.5

Company to Host Live Conference Call and Webcast

The Company’s management team will host a live conference call and webcast at 4:30 p.m. eastern time today to discuss the financial results as well as management’s outlook for the business. The conference call may be accessed in the United States by dialing 1.800.230.1093 and using access code “APKT”. The conference call may be accessed outside of the United States by dialing +1.612.288.0329 and using access code “APKT”. The conference call will be simultaneously webcast on the Company’s investor relations website, which can be accessed at www.ir.acmepacket.com. A replay of the conference call will be available approximately two hours after the call by dialing 1.800.475.6701 or +1.320.365.3844 and using access code 219385 or by accessing the webcast replay on the Company’s investor relations website.

About Acme Packet

Acme Packet (NASDAQ: APKT), the leader in session delivery network solutions, enables the trusted, first-class delivery of next-generation voice, data and unified communications services and applications across IP networks. Our Net-Net product family fulfills demanding security, service assurance and regulatory requirements in service provider, enterprise and contact center networks. Based in Bedford, Massachusetts, Acme Packet designs and manufactures its products in the USA, selling them through over 200 reseller partners worldwide. More than 1,525 customers in 107 countries have deployed over 14,000 Acme Packet systems, including 90 of the top 100 service providers and 36 of the Fortune 100. For more information visit www.acmepacket.com.

Acme Packet, Inc. Safe Harbor Statement

Statements contained herein that are not historical fact (including those in the section “Company Reaffirms Business Outlook for 2011”) may be forward-looking statements within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934. Such forward-looking statements may relate to, among other things, expected financial and operating results, expected growth rates, future stock-based compensation and amortization expenses, future business prospects and market conditions. Such

forward-looking statements do not constitute guarantees of future performance and are subject to a variety of risks and uncertainties that could cause actual results to differ materially from those anticipated. These include, but are not limited to: the amount of stock-based compensation awarded; the applicable Company stock price used to determine stock-based compensation; the exercise pattern of employee stock options; difficulties expanding the Company’s customer base; difficulties leveraging market opportunities; difficulties providing solutions that meet the needs of customers; poor product sales; long sales cycles; difficulties developing new products; difficulties in relationships with vendors and partners; higher risks in international operations; difficulties managing rapid growth; difficulties managing the Company’s financial performance; the ability to hire and retain employees and appropriately staff operations; the Company’s cash needs; the impact of new accounting pronouncements and increased competition. Additional factors that could cause actual results to differ materially from those projected or suggested in any forward-looking statements are contained in the Company’s recent filings with the Securities and Exchange Commission, including those factors discussed under the caption “Risk Factors” in such filings.

Acme Packet, Inc.
Condensed Consolidated Statements of Income
(in thousands, except share and per share data)
(unaudited)

		Three Months Ended								Nine Months Ended
		September 30,								September 30,
		2011				2010				2011				2010
Revenue:
Product		$	53,077			$	45,328			$	177,507			$	129,452
Maintenance, support and service			17,544				11,286				46,814				31,548
Total revenue			70,621				56,614				224,321				161,000
Cost of revenue:
Product			8,778				7,903				30,090				22,886
Maintenance, support and service			3,042				2,556				8,573				6,964
Total cost of revenue			11,820				10,459				38,663				29,850
Gross profit			58,801				46,155				185,658				131,150
Operating expenses:
Sales and marketing			27,201				17,012				75,640				50,062
Research and development			13,249				8,896				37,262				26,235
General and administrative			5,406				3,906				15,771				10,785
Merger and integration-related costs			120				—				300				—
Total operating expenses			45,976				29,814				128,973				87,082
Income from operations			12,825				16,341				56,685				44,068
Other (expense) income, net			(53	)			189				(147	)			354
Income before provision for income taxes			12,772				16,530				56,538				44,422
Provision for income taxes			4,846				6,065				20,895				15,895
Net income		$	7,926			$	10,465			$	35,643			$	28,527
Net income per share:
Basic		$	0.12			$	0.17			$	0.54			$	0.46
Diluted		$	0.11			$	0.15			$	0.50			$	0.43
Weighted average number of common shares used in the calculation of net income per share:
Basic			66,752,669				62,772,466				66,011,761				61,371,085
Diluted			70,908,590				68,426,272				70,887,241				67,114,486
Margin:
Gross margin			83.3	%			81.5	%			82.8	%			81.5	%
Operating margin			18.2	%			28.9	%			25.3	%			27.4	%
Net margin			11.2	%			18.5	%			15.9	%			17.7	%

Acme Packet, Inc.
Condensed Consolidated Balance Sheets
(in thousands)
(unaudited)

		September 30,				December 31,
		2011				2010
Assets
Current assets:
Cash and cash equivalents		$	156,962			$	91,669
Short-term investments			181,660				179,024
Accounts receivable, net			51,246				34,797
Inventory			11,779				6,662
Deferred product costs			1,074				3,572
Deferred tax asset			3,814				3,814
Income taxes receivable			13,404				9,979
Other current assets			6,953				3,231
Total current assets			426,892				332,748
Long-term investments			—				5,030
Property and equipment, net			24,514				17,156
Acquired intangible assets, net			9,095				9,468
Goodwill			3,269				—
Deferred tax asset, net			14,802				14,802
Other assets			425				940
Total assets		$	478,997			$	380,144
Liabilities and Stockholders’ Equity
Current liabilities:
Accounts payable		$	7,056			$	7,161
Accrued expenses and other current liabilities			13,494				14,629
Deferred revenue			28,838				31,998
Total current liabilities			49,388				53,788
Deferred revenue			3,471				1,546
Deferred rent			1,820				4,265
Stockholders’ equity:
Common stock			74				71
Additional paid-in capital			334,254				266,114
Treasury stock, at cost			(37,522	)			(37,522	)
Other comprehensive income			21				34
Accumulated retained earnings			127,491				91,848
Total stockholders’ equity			424,318				320,545
Total liabilities and stockholders’ equity		$	478,997			$	380,144

Condensed Consolidated Statements of Cash Flow
(in thousands)
(unaudited)

		Three Months Ended								Nine Months Ended
		September 30,								September 30
		2011				2010				2011				2010
Cash provided by operating activities		$	16,441			$	9,715			$	36,646			$	32,749
Cash provided by (used in) investing activities			10,516				(4,590	)			(14,486	)			(53,772	)
Cash provided by financing activities			9,434				14,894				43,133				41,194

Acme Packet, Inc.
Statement on Use of Non-GAAP Financial Measures and
Reconciliation of Non-GAAP Net Income and Non-GAAP Net Income Per Share
(in thousands, except share and per share data)
(unaudited)

     Statement on Use of Non-GAAP Financial Measures:

     To supplement its condensed consolidated financial statements presented in accordance with accounting principles generally accepted in the United States (“GAAP”), the Company discloses certain non-GAAP financial measures, including “non-GAAP net income”, “net income on a non-GAAP basis”, “non-GAAP net income per share”, “non-GAAP EPS”, “net income per share on a non-GAAP basis” and “non-GAAP EPS growth rate”. These non-GAAP financial measures are not presented in accordance with GAAP and are not meant to be a substitute for the most directly comparable GAAP measures of “net income”, “EPS”, “GAAP EPS growth rate” or “net income per share”. Rather, these non-GAAP financial measures should be evaluated in conjunction with its most directly comparable GAAP financial measure and the Company’s financial statements as a whole.

     Management uses these supplemental non-GAAP financial measures to evaluate performance period over period, to analyze the underlying trends in the Company’s business, to assess its performance relative to its competitors, and to establish operational goals and forecasts that are used in allocating resources. Management uses these non-GAAP financial measures because they exclude stock-based compensation expense which is a non-cash charge and related payroll taxes, amortization of acquired intangible assets and merger and integration-related costs associated with the Company’s acquisition activities all of which are non-operational costs and expenses. By excluding stock-based compensation expense and related payroll taxes, amortization of acquired intangible assets, and merger and integration-related costs, management can compare the Company’s operations to prior periods and to the operations of other companies in its industry who may have materially different unusual, non-operational charges. Management does not consider any of stock-based compensation expense and related payroll taxes, amortization of acquired intangible assets, and merger and integration-related costs to be part of the Company’s operating activities or meaningful in evaluating the Company’s past financial performance or future prospects. Management believes that excluding these items is useful to investors because it is more representative of ongoing costs and therefore more comparable to historical operations.

     Because management uses them, management believes that the disclosure of these non-GAAP financial measures to investors provides greater transparency and useful information to help the investor better understand the Company’s operating performance and to evaluate the methodology used by management to evaluate and measure such performance. Notwithstanding their utility to investors in understanding operational trends, these non-GAAP measures should not be considered measures of the Company’s liquidity. In addition, the Company cautions that its definition of “non-GAAP net income”, “non-GAAP EPS” and “non-GAAP net income per share” may differ from similar measures used by other companies and may differ from period to period. Also, in future periods, management may make other adjustments for expenses and gains that it does not consider reflective of core operating performance in a particular period thereby modifying its definition of “non-GAAP net income”, “non-GAAP EPS” and “non-GAAP net income per share” by excluding these other or additional expenses and gains.

Acme Packet, Inc.
Non-GAAP Condensed Consolidated Statements of Income
(in thousands, except share and per share data)
(unaudited)

		Three Months Ended								Nine Months Ended
		September 30,								September 30,
		2011				2010				2011				2010
Revenue:
Product		$	53,077			$	45,328			$	177,507			$	129,452
Maintenance, support and service			17,544				11,286				46,814				31,548
Total revenue			70,621				56,614				224,321				161,000
Cost of revenue:
Product			8,066				7,311				27,882				21,172
Maintenance, support and service			2,474				2,268				7,055				6,201
Total cost of revenue			10,540				9,579				34,937				27,373
Gross profit			60,081				47,035				189,384				133,627
Operating expenses:
Sales and marketing			22,316				14,898				62,549				44,448
Research and development			10,309				7,536				29,405				22,459
General and administrative			3,791				3,040				11,873				8,970
Total operating expenses			36,416				25,474				103,827				75,877
Income from operations			23,665				21,561				85,557				57,750
Other (expense) income, net			(53	)			189				(147	)			354
Income before provision for income taxes			23,612				21,750				85,410				58,104
Provision for income taxes			8,964				8,061				31,393				21,232
Net income		$	14,648			$	13,689			$	54,017			$	36,872
Net income per share:
Basic		$	0.22			$	0.22			$	0.82			$	0.60
Diluted		$	0.21			$	0.20			$	0.76			$	0.55
Weighted average number of common shares used in the calculation of net income per share:
Basic			66,752,669				62,772,466				66,011,761				61,371,085
Diluted			70,908,590				68,426,272				70,887,241				67,114,486
Margin:
Gross margin			85.1	%			83.1	%			84.4	%			83.0	%
Operating margin			33.5	%			38.1	%			38.1	%			35.9	%
Net margin			20.7	%			24.2	%			24.1	%			22.9	%

Acme Packet, Inc.
GAAP to Non-GAAP Reconciliation
Three Months Ended September 30, 2011
(in thousands, except share and per share data)
(unaudited)

						Stock-based
						compensation				Amortization of				Merger and
						expense and related				acquired intangible				integration-related
		GAAP				payroll taxes				assets				costs				Non-GAAP1
Revenue:
Product		$	53,077			$	—			$	—			$	—			$	53,077
Maintenance, support and service			17,544				—				—				—				17,544
Total revenue			70,621				—				—				—				70,621
Cost of revenue:
Product			8,778				(327	)			(385	)			—				8,066
Maintenance, support and service			3,042				(568	)			—				—				2,474
Total cost of revenue			11,820				(895	)			(385	)			—				10,540
Gross profit			58,801				895				385				—				60,081
Operating expenses:
Sales and marketing			27,201				(4,784	)			(101	)			—				22,316
Research and development			13,249				(2,929	)			(11	)			—				10,309
General and administrative			5,406				(1,615	)			—				—				3,791
Merger and integration-related costs			120				—				—				(120	)			—
Total operating expenses			45,976				(9,328	)			(112	)			(120	)			36,416
Income from operations			12,825				10,223				497				120				23,665
Other income, net			(53	)			—				—				—				(53	)
Income before provision for income taxes			12,772				10,223				497				120				23,612
Provision for income taxes			4,846				3,896				179				43				8,964
Net income		$	7,926			$	6,327			$	318			$	77			$	14,648
Net income per share:
Basic		$	0.12			$	0.09			$	0.01			$	0.00			$	0.22
Diluted		$	0.11			$	0.09			$	0.01			$	0.00			$	0.21
Weighted average number of common shares used in the calculation of net income per share:
Basic			66,752,669				66,752,669				66,752,669				66,752,669				66,752,669
Diluted			70,908,590				70,908,590				70,908,590				70,908,590				70,908,591
Margin:
Gross margin			83.3	%															85.1	%
Operating margin			18.2	%															33.5	%
Net margin			11.2	%															20.7	%

Acme Packet, Inc.
GAAP to Non-GAAP Reconciliation
Nine Months Ended September 30, 2011
(in thousands, except share and per share data)
(unaudited)

						Stock-based
						compensation				Amortization of				Merger and
						expense and related				acquired intangible				integration-related
		GAAP				payroll taxes				assets				costs				Non-GAAP1
Revenue:
Product		$	177,507			$	—			$	—			$	—			$	177,507
Maintenance, support and service			46,814				—				—				—				46,814
Total revenue			224,321				—				—				—				224,321
Cost of revenue:
Product			30,090				(916	)			(1,292	)			—				27,882
Maintenance, support and service			8,573				(1,518	)			—				—				7,055
Total cost of revenue			38,663				(2,434	)			(1,292	)			—				34,937
Gross profit			185,658				2,434				1,292				—				189,384
Operating expenses:
Sales and marketing			75,640				(12,804	)			(287	)			—				62,549
Research and development			37,262				(7,823	)			(34	)			—				29,405
General and administrative			15,771				(3,898	)			—				—				11,873
Merger and integration-related costs			300				—				—				(300	)			—
Total operating expenses			128,973				(24,525	)			(321	)			(300	)			103,827
Income from operations			56,685				26,959				1,613				300				85,557
Other (expense), net			(147	)			—				—				—				(147	)
Income before provision for income taxes			56,538				26,959				1,613				300				85,410
Provision for income taxes			20,895				9,874				581				43				31,393
Net income		$	35,643			$	17,085			$	1,032			$	257			$	54,017
Net income per share:
Basic		$	0.54			$	0.26			$	0.02			$	0.00			$	0.82
Diluted		$	0.50			$	0.24			$	0.02			$	0.00			$	0.76
Weighted average number of common shares used in the calculation of net income per share:
Basic			66,011,761				66,011,761				66,011,761				66,011,761				66,011,761
Diluted			70,887,241				70,887,241				70,887,241				70,887,241				70,887,241
Margin:
Gross margin			82.8	%															84.4	%
Operating margin			25.3	%															38.1	%
Net margin			15.9	%															24.1	%

Acme Packet, Inc.
GAAP to Non-GAAP Reconciliation
Three Months Ended September 30, 2010
(in thousands, except share and per share data)
(unaudited)

						Stock-based
						compensation				Amortization of
						expense and related				acquired intangible
		GAAP				payroll taxes				assets				Non-GAAP1
Revenue:
Product		$	45,328			$	—			$	—			$	45,328
Maintenance, support and service			11,286				—				—				11,286
Total revenue			56,614				—				—				56,614
Cost of revenue:
Product			7,903				(213	)			(379	)			7,311
Maintenance, support and service			2,556				(288	)			—				2,268
Total cost of revenue			10,459				(501	)			(379	)			9,579
Gross profit			46,155				501				379				47,035
Operating expenses:
Sales and marketing			17,012				(2,069	)			(45	)			14,898
Research and development			8,896				(1,349	)			(11	)			7,536
General and administrative			3,906				(866	)			—				3,040
Total operating expenses			29,814				(4,284	)			(56	)			25,474
Income from operations			16,341				4,785				435				21,561
Other income, net			189				—				—				189
Income before provision for income taxes			16,530				4,785				435				21,750
Provision for income taxes			6,065				1,835				161				8,061
Net income		$	10,465			$	2,950			$	274			$	13,689
Net income per share:
Basic		$	0.17			$	0.04			$	0.01			$	0.22
Diluted		$	0.15			$	0.04			$	0.01			$	0.20
Weighted average number of common shares used in the calculation of net income per share:
Basic			62,772,466				62,772,466				62,772,466				62,772,466
Diluted			68,426,272				68,426,272				68,426,272				68,426,272
Margin:
Gross margin			81.5	%											83.1	%
Operating margin			28.9	%											38.1	%
Net margin			18.5	%											24.2	%

Acme Packet, Inc.
GAAP to Non-GAAP Reconciliation
Nine Months Ended September 30, 2010
(in thousands, except share and per share data)
(unaudited)

						Stock-based
						compensation				Amortization of
						expense and related				acquired intangible
		GAAP				payroll taxes				assets				Non-GAAP1
Revenue:
Product		$	129,452			$	—			$	—			$	129,452
Maintenance, support and service			31,548				—				—				31,548
Total revenue			161,000				—				—				161,000
Cost of revenue:
Product			22,886				(577	)			(1,137	)			21,172
Maintenance, support and service			6,964				(763	)			—				6,201
Total cost of revenue			29,850				(1,340	)			(1,137	)			27,373
Gross profit			131,150				1,340				1,137				133,627
Operating expenses:
Sales and marketing			50,062				(5,479	)			(135	)			44,448
Research and development			26,235				(3,743	)			(33	)			22,459
General and administrative			10,785				(1,815	)			—				8,970
Total operating expenses			87,082				(11,037	)			(168	)			75,877
Income from operations			44,068				12,377				1,305				57,750
Other income, net			354				—				—				354
Income before provision for income taxes			44,422				12,377				1,305				58,104
Provision for income taxes			15,895				4,870				467				21,232
Net income		$	28,527			$	7,507			$	838			$	36,872
Net income per share:
Basic		$	0.46			$	0.12			$	0.01			$	0.60
Diluted		$	0.43			$	0.11			$	0.01			$	0.55
Weighted average number of common shares used in the calculation of net income per share:
Basic			61,371,085				61,371,085				61,371,085				61,371,085
Diluted			67,114,486				67,114,486				67,114,486				67,114,486
Margin:
Gross margin			81.5	%											83.0	%
Operating margin			27.4	%											35.9	%
Net margin			17.7	%											22.9	%

Acme Packet, Inc.
GAAP to Non-GAAP Reconciliation
Three Months Ended June 30, 2011
(in thousands, except share and per share data)
(unaudited)

						Stock-based
						compensation				Amortization of
						expense and related				acquired intangible
		GAAP				payroll taxes				assets				Non-GAAP1
Revenue:
Product		$	64,688			$	—			$	—			$	64,688
Maintenance, support and service			15,045				—				—				15,045
Total revenue			79,733				—				—				79,733
Cost of revenue:
Product			11,367				(327	)			(536	)			10,504
Maintenance, support and service			2,525				(499	)			—				2,026
Total cost of revenue			13,892				(826	)			(536	)			12,530
Gross profit			65,841				826				536				67,203
Operating expenses:
Sales and marketing			24,736				(4,441	)			(140	)			20,155
Research and development			12,719				(2,652	)			(11	)			10,056
General and administrative			5,788				(1,303	)			—				4,485
Total operating expenses			43,243				(8,396	)			(151	)			34,696
Income from operations			22,598				9,222				687				32,507
Other (expense), net			(196	)			—				—				(196	)
Income before provision for income taxes			22,402				9,222				687				32,311
Provision for income taxes			8,394				3,241				246				11,881
Net income		$	14,008			$	5,981			$	441			$	20,430
Net income per share:
Basic		$	0.21			$	0.09			$	0.01			$	0.31
Diluted		$	0.20			$	0.08			$	0.01			$	0.29
Weighted average number of common shares used in the calculation of net income per share:
Basic			66,141,163				66,141,163				66,141,163				66,141,163
Diluted			71,033,614				71,033,614				71,033,614				71,033,614
Margin:
Gross margin			82.6	%											84.3	%
Operating margin			28.3	%											40.8	%
Net margin			17.6	%											25.6	%