How UMA works

If you make a call over the cellular network, like you probably do every day, first your device connects to a tower called a Base Transceiver Station (BTS), and from there the connection goes over a private network to a Base Station Controller (BSC), which further directs your connection to the public telephone network.

With UMA, it works like this: after you've entered a few WLAN connection settings, your UMA-enabled mobile device can connect to the Internet over WLAN. Using IP (Internet Protocol), it then connects to what's called the UMA Network Controller (UNC). Think of your WLAN access point as the BTS, the Internet connection as the private network, and the UNC as the BSC. One of the main differences is that all of the speech and data information is being sent over the Internet connection. And that's it in a nutshell.

Why IP?

UMA isn't the only mobile phone technology that's using IP. UMA is just one example of so-called VoIP (Voice over IP) technologies, such as the popular peer-to-peer Internet telephony. The key idea in all VoIP technologies is the clever use of the latest advances of Internet and broadband technologies to create affordable, reliable voice services. VoIP itself is based on IP, which is the communication language that allows your computer to retrieve information from the Internet. Given that the Internet has become such a huge part of how we communicate and share information, it's not surprising that some creative people decided that it should work for telephony, too.