George Washington University in Washington is testing 25 dual-mode wireless phones that allow users to move to and from indoor wi-fi networks to outdoor cellular networks.

Potentially, the university could support up to 30,000 of the dual-mode phones for use by students and staff on three campuses – if the technology proves reliable and saves on expensive cellular minute costs by allowing users to call over university-controlled wi-fi networks, said Bret Jones, GWU director of technology and engineering.

The test, which began recently, uses Nokia E61 phones equipped with client software from Avaya. Called Avaya one-X Mobile Dual-Mode, the software is being unveiled today, Avaya officials said. Each client costs $160 (£78) per user, and can be downloaded from Avaya’s website.

The Avaya client gives a user access to Avaya IP-based applications on the Avaya Communications Manager IP-PBX switch, allowing one office number – instead of a second cellular phone number – to handle conference calls, speed dialing and speech activation of applications, Jones said. Avaya also requires SIP Enablement Server software as part of the system.

Several vendors have announced dual-mode systems, which Jones said he examined before picking Avaya. “But Avaya is very strong and I've been real happy with their products,” he said.

Avaya described the one-X Mobile dual-mode capability as the ability to switch between cellular and WLAN connectivity “without losing the call”. But Jones said moving between the networks has resulted in delays for the testers.

“As you move across a boundary, the call doesn’t disconnect, but it does delay,” Jones said. “That’s one of the challenges.”

The delay problem could be improved with more cooperation from cellular network providers, Jones said. “They are not really supportive of this technology for obvious revenue reasons. Anytime a cell phone is on wi-fi means they are not collecting cell minutes. That is one of the biggest challenges with this technology.”

Cellular network operators are testing and developing their own dual-mode systems, in which they provide software to smoothly link a phone call from a wi-fi to a cellular network, and might eventually sell dual-mode phones that are locked to their own network with a multiyear subscription plan, several analysts said.

T-Mobile USA launched a trial of such a system in October in the Seattle area and T-Mobile USA launched the HotSpot Home service nationally in June.

Jones said there are “several challenges” in getting the dual-mode phones to make a smooth transition from wi-fi to cellular, and there are “different issues with different carriers” because they have different networks with varying levels of service.

But the chief advantage of having a single phone that works on both networks, is not lost on Jones, who said an employee can move between campuses that are miles apart with a single phone. “It increases mobility and makes the cell phone an extension of the office phone with all the function of the office phone,” he said.

Jones said that if the testing goes well, GWU might start implementing a rollout of some dual-mode phones to staffers in the fall of 2009. At $400 (£196) for each phone – and added expenses for software – the university would not expect students to pay for all the costs. “Until the cellular providers support this technology, we won’t see subsidised phones and that’s a big concern,” he said.

The Avaya system requires a “one-touch” handoff between wi-fi and a GSM cellular network, according to Avaya documents. A user might be asked to hand over the active call to GSM or wi-fi, and would click a Yes button on the handset.

Several major vendors have announced dual-mode software and more than 100 dual-mode phones are now on the market, analysts said. The connection software that supports a voice switch has already been announced by Siemens, Ericsson, Cisco Systems and others, analysts said.

“Clearly, dual-mode systems would save money for an enterprise or campus when it comes to mobile users spending considerable time in an office or on the road,” said Brian Riggs, an analyst at Current Analysis. The most basic value of a dual-mode system “would be to prevent John from calling Frank on the third floor from the second floor while using the cell phone minute plan”.

Riggs and Jones said an effective dual-mode system will probably require an upgrade to the wi-fi system to provide complete coverage, but also to include software that prioritises voice traffic over data traffic. “Ubiquitous wireless is our strategy,” Jones said.