Worldwide sales of WiFi phones jumped 61 per cent in 2007, as more companies embraced the cost and convenience benefits of using wireless voice over IP (VoIP) for internal calls.

Figures compiled by market research firm Infonetics suggest that single-mode WiFi-only handsets are being deployed instead of desktop phones in campuses and large office environments, where the costs of deploying wireless LAN (WLANs) and WiFi phones is less than installing both data and voice telephone networks.

The trend looks set to continue with the increased availability of WiFi-enabled smartphones, such as the iPhone and WiFi BlackBerry. These combine private WLAN and hotspot connectivity with the ability to make GSM calls when outside WiFi range.

BT is offering its corporate Fusion service, which uses dual mode WiFi/GSM phones to replace existing mobile and desktop phones in offices.

Infonetics estimates that worldwide sales of all wireless LAN equipment, including independent and dependent access points and WLAN switches and controllers, hit $1.9bn (£952m) in 2007, up 20 per cent from 2006.