Integrating mobile phones into a corporate wireless local area network was a feature of the 3GSM conference in Barcelona.
Nokia was one of the handset suppliers that showed conference delegates a new phone that can switch calls seamlessly between cellular and wireless (Wi-Fi) networks as the user roams.
The main benefit of converged handsets for business users is significantly lower call costs - because calls are routed via IP over a wireless broadband internet connection.
Users also stand to gain better productivity from features such as unified messaging, having a single phone number, presence-based services, and access to one set of contacts and groupware applications in and out of the office.
"Internet voice is going mobile," said Nokia's chief executive officer, Jorma Ollila, at the launch of the N6136 handset.
However, Nokia has yet to sign up any operators for its phone, and has no customers so far.
Frank Hanzlik, managing director of non-profit industry group the WiFi Alliance, said, "Voice over Wi-Fi is at an early stage. However, Skype has created the grass-roots interest and VoIP is not going away. We have certified 20 devices for convergence over the last year."
Hanzlik said industry standards body the Institute of Electrical and Electronics Engineers is planning to standardise a version of the 802.11 Wi-Fi protocol, which will hand off the signal from 3G to Wi-Fi without requiring proprietary technology. The new protocol - 802.11u - should be included in products in 2008.
"By the end of this year all of Nokia's platforms will have Wi-Fi," said Hanzlik. "Over time, people are going to take for granted the fact that their devices use a variety of networks and technologies to stay connected."
Operators and technology suppliers have been piloting the technology, with the likes of BT, Avaya and Cisco claiming success with their pilots.
Earlier this month, BT started to sell a converged handset package to businesses based on its BT Fusion consumer service. It uses one handset and passes calls between fixed and mobile networks, depending on the user's location.
O2 and Orange plan to experiment with this technology, but are not rushing to provide services to businesses. O2's chief technology officer, Dave Williams, said, "It's early days for convergence technology. We will develop converged networks from 2008. Is cheap voice the killer application?" We've got that today."