BT is preparing to launch a new service that will allow its customers to use their home or office phone number across their smartphones, PCs or VoIP-enabled telephones.

BT One Voice Anywhere is based on technology from Ribbit, a Silicon Valley start-up BT acquired in 2008 for $105 million. Ribbit’s ‘SmartSwitch’ technology is a software switching platorm that can be used to build voice applications.

Clients will be available for Android, Apple and BlackBerry devices, PCs and IP phones that support the SIP (session initiation protocol) standard.

The new service will be available in "four to five weeks", programme director Martin Rolls told Information Age. Pricing details are still being finalised.

BT is already using the system internally. "At BT, our people don’t sit at a single desk any more,” Rolls said. “Day to day they are in different buildings, sometimes mobile, sometimes fixed. Having a single number that is accessible from wherever you are is a very important thing."

Using the service will help BT cut its mobile telephony costs, Rolls claimed. “As a large corporate, we do spend a fairly significant sum of money on mobile telephony, and there’s an opportunity here to reduce costs.”

He said that customers will benefit from the fact that BT operates its own network infrastructure. "We feel that the fact we own all our own wires is our unique selling point," he said. "We take advantage of the network at low cost internally, and give that advantage to our customers."

BT killed off its previous VoiP programme, Broadband Talk, in February 2011, one month before development on BT One Voice began. At the time, Mayuresh Thavapalan, BT’s general manager for consumer broadband, said that the cost advantage of being of VoIP service had diminished. "When the service launched in 2006-2007, it was much more significant in terms of tariff.

Google has a comparable service to BT One Voice Anywhere, called Google Voice, but not all functionality is available in the UK.