Universal Mobile Telecommunications System (UMTS), is the third generation (3G) successor to the second generation GSM based cellular technologies which also include GPRS, and EDGE. Although UMTS uses a totally different air interface, the core network elements have been migrating towards the UMTS requirements with the introduction of GPRS and EDGE. In this way the transition from GSM to the 3G UMTS architecture did not require such a large instantaneous investment.
UMTS uses Wideband CDMA (WCDMA or W-CDMA) to carry the radio transmissions, and often the system is referred to by the name WCDMA. It is also gaining a third name. Some are calling it 3GSM because it is a 3G migration for GSM.