Acme Packet Inc. said Thursday that its third-quarter profit nearly tripled as sales of its communications equipment grew.

The company, whose results came in ahead of analyst estimates, also raised its forecast for the rest of the year. However, the upside seemed not to excite investors, who pushed Acme Packet's stock down 5 percent in after-hours trading.

For the quarter that ended Sept. 30, Acme Packet earned $10.5 million, or 15 cents per share, up from $3.6 million, or 6 cents per share, in the year-ago quarter. Excluding one-time items, the company earned 20 cents per share — a penny higher than what analysts polled by Thomson Reuters expected.

Revenue jumped 56 percent to $56.6 million, also beating analyst estimates of $55 million.

Acme Packet said product revenue rose nearly 64 percent to $45.3 million, while maintenance, support and service revenue rose 31 percent to $11.3 million.

Acme Packet also raised its outlook for the rest of the year. The company now expects a profit of 59 cents or 60 cents per share, or 76 cents or 77 cents excluding one-time items, on $220 million to $221 million in revenue. Previously, the company predicted a profit of 72 cents to 74 cents excluding one-time items, on $214 million to $218 million in revenue.

Analysts are looking for an adjusted profit of 73 cents per share on $218 million in revenue, on average.

Acme Packet shares fell $2.13, or 5.4 percent, to $36.90 in after-hours trading. The stock had fallen 54 cents to close the regular session at $39.69.