From Forum Nokia Wiki

UMTS: stands for Universal Mobile Telecommunications System - and is one of the third-generation (3G) mobile phone technologies.

Currently, the most common form uses WCDMA as the underlying air interface, is standardized by the 3GPP, and is the European answer to the ITU IMT-2000 requirements for 3G cellular radio systems.

To differentiate UMTS from competing network technologies, UMTS is sometimes marketed as 3GSM, emphasizing the combination of the 3G nature of the technology and the GSM standard which it was designed to succeed.

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