That holy grail of wireless/IP convergence, the seamless handoff of a dual-mode phone call from a Wi-Fi network to a cellular network, is still a rare phenomenon in most places. But we are taking small steps towards it now, in the form of a new class of specialized Wi-Fi access points designed to support voice-over-IP.

Connected to a VoIP network and phone service, these access points provide VoIP's cheaper services to cellular phone users within range of their Wi-Fi transmitters. They may also offer better-than-cellular indoor coverage.

If the user leaves the zone of Wi-Fi coverage, and if (but only if) his or her mobile operator supports such services, these devices will also hand off calls from Wi-Fi to cellular. Motorola's recently-announced RSG system, expected by late this year, exemplifies the trend.

"If such products prove successful," says Philip Solis, senior analyst of wireless connectivity research at ABI Research, "it will validate the idea and the importance of voice-over-Wi-Fi. Even a system providing a limited service, without operator-supported handoffs, offers rewards in the form of cheaper calls and better indoor coverage."

If these VoIP/Wi-Fi access products enjoy considerable market success, that would also support analysts' forecasts of a boom in dual-mode cellular/VoWi-Fi devices.

But much work remains to be done by all industry stakeholders to arrange how services are charged and minutes billed, before seamless handoffs become an attractive proposition to most carriers.

Solis adds, "ABI Research would urge mobile operators who lag behind in offering converged services to pick up the pace, or risk losing revenue to their nimbler competitors, or because their customers find lower-cost workarounds."

ABI Research's study, "Voice over Wi-Fi: Market Dynamics for Enterprise and Consumer VoWi-Fi, and Dual-mode Cellular/VoWi-Fi Handsets" examines the whole industry, from chipset providers to service providers. Supported by forecasts and tables, it discusses the technologies involved, the consortia driving these handsets, and the competitive business environment.

It forms part of the company's subscription Wi-Fi Research Service, which also includes research reports, ABI Insights, forecast databases and regular market updates.

Founded in 1990 and headquartered in New York, ABI Research maintains global operations supporting annual research programs, intelligence services and market reports in automotive, wireless, semiconductors, broadband, and energy. For information visit www.abiresearch.com, or call +1.516.624.2500.