Cisco Systems will acquire Jabber. The purchase of the open source instant messaging company will help Cisco increase its communications and collaboration portfolio.

The corporation, which has about 66,000 employees, said in a Friday-released statement it intended to deploy Jabber’s software to its WebEx Connect and Unified Communications.

The financial details of the deal remain undisclosed, but the purchase follows a series of similar moves by Cisco Systems. After buying Cerent Corp, Stratacom, Scientific-Atlanta and Linksys, Cisco did the same last month with Web conferencing and video conferencing applications provider WebEx Communications Incorporated. In August 2008, Cisco also acquired PostPath Inc for $215 million.

Back to Jabber. The Denver-based company’s messaging software supports AOL AIM, Microsoft Office Communications Server and IBM Sametime. It is also compatible with instant messaging software from Gizmo, Google and Yahoo. Cisco will certainly use Jabber’s technology to complement the WebEx platform.

Having diversified its array of collaboration products, Cisco is now at the same level with giants such as Microsoft, I.B.M., Yahoo and Google. The company’s CEO John Chambers said Cisco Systems intends to win the competition on the collaboration market, Microsoft and IBM.

“Both Microsoft and I.B.M. are important partners to Cisco in many parts of our business. I think the collaboration part is an area where there is overlap, and our objective is to make that as seamless as possible,” said Charles Carmel, vice president of corporate development for Cisco.