Cisco and Nokia announced new dual-mode smart phones that can operate on a Cisco enterprise VoIP infrastructure and a public GSM network.

The dual-mode Nokia E61i and E65 smart phones contain both 802.11g and GSM radios, as well as software that allows the devices to sense which network signal is strongest and place calls accordingly. The Nokia handsets also have software allowing them to operate as a corporate phone extension off of a Cisco CallManager IP PBX and messaging infrastructure. The new phones were announced at 3GSM World Congress in Barcelona this week.

Cisco kicked off its partnership with Nokia last year, when it announced compatibility between Cisco's Unified CallManager 5.0 system and Nokia E60, E61 and E70 smart phones. This interoperability allows a Nokia phone to receive VoIP calls switched via a Cisco IP PBX, the same as a wired desktop IP phone, or a Cisco 802.11-based handset.

The race to link cellphones with corporate VoIP systems has heated up recently among IP PBX makers. In the fall, Avaya and Cisco both acquired companies that allow cellphones and smart phones to access corporate VoIP networks and messaging applications. Avaya bet $15 million on Traverse Networks, a maker of fixed-mobile convergence software for cellphones, last November. The month before, Cisco bought Orative Corp., which makes similar software, for $31 million.