Unlicensed Mobile Access (UMA) technology provides access to GSM and data mobile services over the internet. It uses Wi-Fi (802.11b/g) to connect a mobile handset to a broadband internet connection. Using UMA technology, T-Mobile can enable subscribers to freely move between cellular networks and public and private unlicensed wireless networks (Wi-Fi) using dual-mode mobile handsets. With UMA, you receive a consistent user experience for your mobile voice and data services as you transition between networks.
How UMA works
The first thing a UMA enabled handset does when entering range of a Wi-Fi network is attempt to connect to that network’s Wireless Router (WR) in order to get internet access. Once connected to the internet, the handset sets up a secure tunnel all the way to T-Mobile's network (the Security Gateway). If the subscriber is authenticated and authorized for UMA service, the handset is connected to T-Mobile's network, via the UMA Network Controller or UNC and is ready to provide service to you.
How UMA is different from GSM
The difference between this connection and a standard GSM connection is that the UMA handset does not route calls through our GSM radio towers. Instead the phone creates a virtual GSM connection over the internet. By routing calls over the internet instead of through our towers it helps manage network congestion and capacity related issues.