Cisco on Friday said it intends to acquire messaging software maker Jabber, filling an important gap in Cisco's technology arsenal as it battles Microsoft in the unified communications market. Financial terms were not disclosed.

Jabber's open source instant messaging and presence technology enables collaboration across a variety of enterprise communication systems, such as Microsoft Office Communications Server and IBM Lotus Sametime. Jabber also integrates with online mail and IM services from AOL, Google, and Yahoo.

Within the enterprise, Cisco is in a race with Microsoft to become the leading supplier of unified communications technology, which combines voice with e-mail, instant messaging, and other data communications. Today, Cisco is the market leader for real-time voice communications, and Microsoft leads in data communications.

In buying Jabber, Cisco gets a bridge between its Unified Communications Manager, an IP-PBX system, and Microsoft's Office Communications Server or IBM Lotus Sametime. This gives Cisco the opportunity insert its technology into what enterprises already have, and try to convince them to move to an all-Cisco communications system later.

"With the acquisition of Jabber, we will be able to extend the reach of our current instant messaging service and expand the capabilities of our collaboration platform," Doug Dennerline, senior VP for Cisco's Collaboration Software Group, said in a statement. "Our intention is to be the interoperability benchmark in the collaboration space."

Cisco expects to close the transaction by January. Once the deal is completed, Jabber employees will join Cisco's Collaboration Software Group.

The Jabber announcement follows less than a month after Cisco announced plans to acquire PostPath, which makes a Linux-based messaging and collaboration server, for $215 million. PostPath has positioned the product as either a replacement or complement to Microsoft Exchange Server. PostPath interoperates natively with Exchange and Outlook, and also with Active Directory and other systems, such as Research In Motion's BlackBerry Enterprise Server.

To better understand the unified communications marketplace, InformationWeek has published an independent analysis of how companies are integrating UC into existing business processes to spur employee usage. Download the report here (registration required).