24.1. 3GPP and IMS

The 3rd Generation Partnership Project (3GPP) is a collaboration agreement signed in 1999 by a number of telecommunications standards bodies—namely, ARIB, CCSA, ETSI, ATIS, TTA, and TTC.^[1]

^[1] ARIB (Association of Radio Industries and Business), CCSA (China Communications Standards Association), ETSI (European Telecommunications Standards Institute), ATIS (Alliance for Telecommunications Industry Solutions), TTA (Telecommunications Technology Association), TTC (Telecommunications Technology Committee).

The main goal of 3GPP is the specification of a third-generation mobile system comprising W-CDMA and TD-CDMA^[2] radio access and an evolved GSM^[3] core network. Such a third-generation mobile system is called UMTS (Universal Mobile Telecommunications System). The 3GPP is also responsible for maintaining and further developing the GSM specifications, which were originally developed by ETSI.

^[2] W-CDMA: Wideband Code Division Multiple Access, TD-CDMA: Time Division/Code Division Multiple Access.

^[3] Global System for Mobile communications. It is representative of the so-called second-generation mobile systems (2G).