The $29.25 per share offer is at a 22 percent premium to Acme Packet's Friday close on the Nasdaq. The deal value is based on the number of outstanding shares as of Dec. 31.
Oracle Chief Executive Larry Ellison, who has boosted Oracle's revenue dramatically over the past decade helped by a series of acquisitions, said in October he would not rule out a big deal "down the road." (See video of CNBC Ellison interview here.)
The company's last acquisition was cloud computing firm Eloqua, which it bought for $810 million in December.
Acme Packet is a provider of session border control technology, which enables delivery of voice, data and unified communications services and applications across IP networks.
"The proposed acquisition of Acme Packet is another important piece in Oracle's overall strategy to deliver integrated best-in-class products that address critical customer requirements in key industries," said Oracle President Mark Hurd. "The addition of Acme Packet to Oracle's leading communications portfolio will enable service providers and enterprises to deliver innovative solutions that will change the way we interact, conduct commerce, deliver healthcare, secure our homes, and much more."
Acme Packet's board has unanimously approved the transaction, which is subject to shareholder and regulatory approval and is expected to close in the first half of 2013.
Acme reported fourth-quarter earnings of 9 cents per share, excluding items, on revenue of $70.7 million. Analysts expected an adjusted profit of 8 cents per share and revenue of $68.9 million, according to Thomson Reuters.
Acme has been hit by weak telecom spending in the last few quarters as carriers spend less on new projects and delay existing ones. Its shares have fallen 18 percent in the last year.