Exhibit 99.1

Acme Packet Reports Results for Third Quarter of 2012

– Company Updates Outlook for 2012 –

Bedford, Massachusetts – October 25, 2012 — Acme Packet, Inc. (NASDAQ: APKT), the leader in session delivery network solutions, today announced results for the third quarter of 2012 and updated its business outlook for 2012. All earnings per share results are on a fully diluted basis.

Results for the Third Quarter of 2012

Total revenue for the third quarter of 2012 was $65.3 million, compared to $70.6 million in the third quarter of 2011 and $67.6 million in the second quarter of 2012. GAAP net loss for the third quarter of 2012 was $5.5 million, or $(0.08) per share, compared to GAAP net income of $7.9 million, or $0.11 per share, in the third quarter of 2011 and GAAP net loss of $0.1 million, or $(0.00) per share, in the second quarter of 2012. Net income on a non-GAAP¹ basis for the third quarter of 2012 was $4.7 million, or $0.07 per share, compared to $14.6 million, or $0.21 per share, in the third quarter of 2011, and $9.5 million, or $0.13 per share, in the second quarter of 2012.

Company Updates Business Outlook for 2012

The Company today updated its business outlook for 2012. 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-GAAP business outlook, and a statement as to the use of non-GAAP financial measures, is included at the end of this press release.

Company to Host Live Conference Call and Webcast

The Company’s management team plans to 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 1.800.230.1085 and using access code “APKT”. The conference call may be accessed outside of the United States by dialing +1.612.234.9960 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 265599 or by accessing the webcast replay on the Company’s investor relations website.

¹A reconciliation of GAAP to non-GAAP results, and a statement on the use of non-GAAP financial measures, is included at the end of this press release.

About Acme Packet

Acme Packet (NASDAQ: APKT), the leader in session delivery network solutions, enables the trusted, first-class delivery of next-generation voice, video, 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 primarily in the USA, selling them through over 309 reseller partners worldwide. More than 1,850 customers in 109 countries have deployed over 20,000 Acme Packet systems, including 89 of the top 100 service providers and 48 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 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 Operations

(in thousands, except share and per share data)

(unaudited)

Acme Packet, Inc.

Condensed Consolidated Balance Sheets

(in thousands)

(unaudited)

Condensed Consolidated Statements of Cash Flow Data

(in thousands)

(unaudited)

Acme Packet, Inc.

Statement on Use of Non-GAAP Financial Measures and

Reconciliation of Non-GAAP Net (Loss) Income and Non-GAAP Net (Loss) 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 statements of operations 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 (loss) income”, “net (loss) income on a non-GAAP basis”, “non-GAAP EPS”, and “net (loss) income per share on a non-GAAP basis”. 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 (loss) income”, “EPS” or “net (loss) 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 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 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 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 (loss) income”, “net (loss) income on a non-GAAP basis”, “non-GAAP EPS” and “net (loss) income per share on a non-GAAP basis” 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 (loss) income”, “non-GAAP EPS” and “non-GAAP net (loss) income per share” by excluding these other or additional expenses and gains.

Reconciliation of GAAP to Non-GAAP Financial Measures for the Three Months Ended September 30, 2012, June 30, 2012 and September 30, 2011 and for the Nine Months Ended September 30, 2012 and September 30, 2011:

Acme Packet, Inc.

Reconciliation of GAAP to Non-GAAP Financial Measures

Three Months Ended September 30, 2012

(in thousands, except per share data)

(unaudited)

Acme Packet, Inc.

Reconciliation of GAAP to Non-GAAP Financial Measures

Three Months Ended June 30, 2012

(in thousands, except per share data)

(unaudited)

Acme Packet, Inc.

Reconciliation of GAAP to Non-GAAP Financial Measures

Three Months Ended September 30, 2011

(in thousands, except per share data)

(unaudited)

Acme Packet, Inc.

Reconciliation of GAAP to Non-GAAP Financial Measures

Nine Months Ended September 30, 2012

(in thousands, except per share data)

(unaudited)

Acme Packet, Inc.

Reconciliation of GAAP to Non-GAAP Financial Measures

Nine Months Ended September 30, 2011

(in thousands, except per share data)

(unaudited)

Reconciliation of Expected Non-GAAP Net Income and Non-GAAP Net Income Per Share for the Year Ending December 31, 2012 (unaudited):

Acme Packet, Inc.

Other Operational Data

(unaudited)