RIM and Cisco Systems have agreed to let enterprises integrate their BlackBerrys with Cisco IP phones, providing single-number capability and other features.

The integration comes in the form of RIM's BlackBerry Mobile Voice System (MVS) Server for Cisco Unified Communications Manager. It brings together the top enterprise mobile platform with the dominant networking vendor's IP voice and messaging system.

Unified communications, a concept Cisco has aggressively pushed, is aimed in part at making individuals reachable anywhere, so mobile devices are a key element of the picture.

RIM introduced the MVS Server last year after developing it from technology it acquired through the purchase of Ascendent Systems in 2007. It developed BlackBerry MVS Server for Cisco Unified Communications Manager through Cisco's Technology Developer Program.

RIM announced the deal as it geared up to meet customers at its Wireless Enterprise Symposium in Orlando, Florida. Also on Monday, the company announced a business software partnership with Hewlett-Packard, a push API for consumer application developers and the availability of BlackBerry Enterprise Server 5.0.

By bringing together their BlackBerry and Cisco infrastructures, enterprises can make users reachable with one number, one caller ID and one voicemail box for both their mobile and desk phones. When calls come in, they may ring simultaneously on as many as four devices, including BlackBerrys and Cisco IP desk phones, or ring one device after another in a sequence. Alternatively, employees can make calls out from the BlackBerry using either the smartphone's own number or an enterprise line.

The deal also brings to BlackBerrys the functions that workers are used to on their desk phones, including extension calling and transfers. In addition, they can also move a call from the mobile to the desk phone while it's in progress, according to RIM.

BlackBerry MVS for Cisco Unified Communications Manager will be available for North American customers in the third quarter of this year and require BlackBerry Enterprise Server 4.1.5 or later and Cisco Unified Communications Manager 6.1 or later. The MVS client software will run on phones with BlackBerry Device Software 4.5 or later.

Other versions of BlackBerry MVS Server are already available for a variety of enterprise voice systems, including hybrid circuit-switched and IP systems.