The PBX-to-mobile market is heating up with a Nokia-backed announcement of a "generic" integrator that allows desk phones on leading switchboards to converge with mobiles on any network in any country.

UK-based On Relay, run by the former IP director of Norway's Telenor, said its software-only MBX product was the first "generic solution" to fully integrate a corporate switchboard and related systems with 3G and GSM smartphones. Nokia said it would jointly market the product.

The announcement follows one from Avaya last month which said it had developed and demonstrated a program that turned a Nokia Series 60 smartphone into an extension on a corporate PBX. On Relay said its MBX integrated into both IP and TDM PBXs from leading vendors including Avaya, Nortel, Cisco and Siemens and worked over virtually any mobile network anywhere in the world. It would even work with full functions while the user was roaming, the company said.

However it is only initially available for Nokia Series 60 devices. Work is underway on future generations of Nokia enterprise devices, the company said, and it has demonstrated it on other phones. On Relay's chief executive Ivar Plahte said Nokia would provide customers with a range of complementary enterprise solutions to allow them to scale MBX alongside large and managed smartphone deployments.

Jaakko Olkkonen, Nokia's general manager for Enterprise Voice Solutions, said Nokia was looking at a "fundamentally new way to marry the best of fixed and mobile telephony to provide cost savings and productivity to businesses and employees... and simplicity and freedom for people in or out of the office."

He said Nokia would be collaborating closely with established leaders in enterprise IP communications, as well as early innovators like OnRelay, to help drive enterprise mobility. "One business number, one voice mail, intelligent call handling and assistant-answered lines are just a few examples of what will be possible in a converged fixed-mobile enterprise voice service," Olkkonen added.

On Relay said users would be able to make and receive calls from both their personal mobile number and their office number using a single mobile device. They maintain all the functions of an office extension including interfacing with directories and customer databases. Outgoing and incoming business calls look to customers - and to internal IT systems - as they have been made or received on the desk phone. But bills for personal calls on the mobile can be kept separate and users can "turn off" their office phone when they finish work and take their mobile home.

Nokia, in a series of announcements today, also said it was licensing Cisco technology to integrate its Series 60 devices, and eventually other devices, to Cisco CallManager over WiFi. IBM, as a systems integrator, was also collaborating with Nokia, Cisco, and OnRelay on mobile convergence, Nokia said.

Jeremy Green, principal enterprise mobility analyst at market researcher Ovum, said corporate telecoms managers wanted tools for managing mobile usage in the company and this kind of product from On Relay would allow them to integrate rules - such as no international calls - and billing on one platform.

He said that large companies were finding it increasingly difficult to integrate the two completely different communications infrastructures. Mobiles had appeared ad hoc, with staff sometimes getting their own phone and putting the bills on expenses with no centralised contracts, for example.

"If you have a communications-centric organisation, such as a dealing room or a bank, you can have regulatory requirements that demand that all calls be monitored, for example," Dr Green said. "The last thing you want is another phone. It can be catastrophic."

In a separate announcement, Nokia said it was developing a new browser for mobile devices based on the same open source components as Apple's Safari desktop browser. The Finnish telecoms equipment maker said it would continue to collaborate with Apple and actively participate in the open source community to enhance those components. It said the entire Series 60 value chain, from manufacturers and operators to end-users, would benefit from the flexible open source architecture that was speedy to develop.

It said its new browser was aimed at "an unparalleled user experience" when browsing full Web pages on a smartphone screen.