Cisco and Nokia have announced dual-mode smartphones that work on a Cisco-based VoIP network as well as public GSM networks.

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.

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 intensified recently among IP PBX makers. In the fourth quarter of 2006, 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.

While Nortel has remained quite on the FMC front, industry observers say a tighter connection between Nortel's corporate VoIP technology and Microsoft's smart phone/handheld software is a reasonable expectation, given the two companies' Innovative Technology Alliance, a four-year product development, sales and support partnership.

Enterprises are interested in melding users' mobile phones with corporate telephony for several reasons. Some say an enterprise with a large base of mobile users can cut cellular costs by allowing employees to make calls more cheaply over a corporate VoIP-enabled Wi-Fi network, or at Wi-Fi hot spots or public wireless networks.

Tying mobile phones closely to a corporate VoIP network also can provide the convenience of a single phone number for employees. In addition, administrators could gain more centralised control over corporate data - such as e-mails, contact databases and voicemails - which normally spread out across individual workers' phones.