The BlackBerry Mobile Voice System (MVS) expands on software RIM got last year through its acquisition of Ascendent Systems, which lets any cell phone act like an office phone, said David Yach, senior vice president of software at RIM. The Ascendent Voice Mobility Suite makes cell phones communicate with enterprise private branch exchanges (PBXes), including both traditional and IP systems. This gives employees a single number where they can be reached anywhere, because calls can ring on both the desk phone and the cell phone.

Fixed-mobile convergence in enterprises is intended to free workers from their desks and cut down on the number of missed calls. Some vendors are pursuing it with dual-mode cellular/Wi-Fi phones to improve indoor coverage and slash phone bills. The BlackBerry MVS is not designed for such dual-mode phones, but there is a huge potential market for a system designed around RIM's popular business devices. All current BlackBerrys have voice capability.

RIM built on Ascendent's one-size-fits-all product to create software that makes it easier to integrate RIM's own products into enterprise phone systems, Yach said. The MVS consists of software components for BlackBerry handhelds and the BlackBerry Enterprise Server, as well as the Ascendent Voice Mobility Suite. With it, administrators can centrally manage the devices and set policies for them, such as requiring all calls made from a handset to go through the PBX for billing and auditing. It also includes the security features of the Blackberry Enterprise Server so each device can be authenticated and unauthorized handsets can't get into the phone system, Yach said.

Employees can use all the PBX features they are used to on their desk phones, such as extensions and conference calling, through an interface built into the familiar BlackBerry client software.

"It just looks, smells and feels like you're using the BlackBerry," Yach said.

RIM is showing off the MVS at the Wireless Enterprise Symposium 2007 in Orlando, and will make it available later this month as a free software update for RIM servers and current BlackBerry phones. Making it work with traditional time-division multiplexing PBXes requires an Ascendent gateway device. Older RIM handsets can work with Ascendent's system but may not support all the features of the MVS, Yach said.