Time-Division Synchronous Code-Division Multiple Access (TD-SCDMA) is an extension to the 3G Universal Mobile Telecommunications System (UMTS), which is the 3G successor of the 2G Global System for Mobile Communications (GSM) and a competitor to the Code-Division Multiple Access 2000 (CDMA2000) standard. TD-SCDMA was only used in China. UMTS evolved into the 4G Long-Term Evolution (LTE), which was also adopted by CDMA networks.