Universal Mobile Access or UMA in short is a technology that allows us to use our GSM phone on accessible WiFi, WiMax and Bluetooth networks. The network devices become like mini cell sites. It is a standard accepted by the members of the 3rd Generation Partnership Project (3GPP)

The UMA enabled mobile has GSM and WiFi radios that can work simultaneously. When the phone moves into the range of a Wireless LAN which is connected to internet, the user connects to the UMA Network Controller (UNC). The UNC authenticates and authorizes the user and updates the IP and MAC address on the central network of the mobile service provider. Once this is done, all GSM services are routed through IP to the location of the user. The switching of network happens seamlessly and automatically, without the user's knowledge.

UMA reduces the burden on cellular towers, and covers poor-coverage areas such as inside buildings, tunnels, and basements. It reduces the transmission costs of calls as well. Users will experience fewer call drops, better voice clarity and increased browsing speeds.

UMA is implemented in US by T-Mobile with 8,500 WiFi hotspots. TeliaSonera, a telecom company, provides the service in Norway, Finland and Sweden. Nokia is planning to release UMA based mobiles by the first quarter of 2008.