General Packet Radio Service in the context of Wireless Application Protocol

The Global System for Mobile Communications (GSM) is a family of standards to describe the protocols for second-generation (2G) digital cellular networks, as used by mobile devices such as mobile phones and mobile broadband modems. GSM is also a trade mark owned by the GSM Association. "GSM" may also refer to the voice codec initially used in GSM.

2G networks developed as a replacement for first generation (1G) analog cellular networks. The original GSM standard, which was developed by the European Telecommunications Standards Institute (ETSI), originally described a digital, circuit-switched network optimized for full duplex voice telephony, employing time division multiple access (TDMA) between stations. This expanded over time to include data communications, first by circuit-switched transport, then by packet data transport via its upgraded standards, GPRS and then EDGE. GSM exists in various versions based on the frequency bands used.

3G refers to the third generation of cellular network technology. These networks were rolled out beginning in the early 2000s and represented a significant advancement over the second generation (2G), particularly in terms of data transfer speeds and mobile internet capabilities. The major 3G standards are UMTS (developed by 3GPP, succeeding GSM) and CDMA2000 (developed by Qualcomm, succeeding cdmaOne); both of these are based on the IMT-2000 specifications established by the International Telecommunication Union (ITU).

While 2G networks such as GPRS and EDGE supported limited data services, 3G introduced significantly higher-speed mobile internet and enhanced multimedia capabilities, in addition to improved voice quality. It provided moderate internet speeds suitable for general web browsing and multimedia content including video calling and mobile TV, supporting services that provide an information transfer rate of at least 144 kbit/s.

In communications, Circuit Switched Data (CSD) (also named GSM data) is the original form of data transmission developed for the time-division multiple access (TDMA)-based mobile phone systems like Global System for Mobile Communications (GSM). In later years, High Speed Circuit Switched Data (HSCSD) was developed providing increased data rates over conventional CSD. After 2010 many telecommunication carriers dropped support for CSD and HSCSD, having been superseded by GPRS and EDGE (E-GPRS).

Enhanced Data rates for GSM Evolution (EDGE), also known as 2.75G and under various other names, is a 2G digital mobile phone technology for packet switched data transmission. It is a subset of General Packet Radio Service (GPRS) on the GSM network and improves upon it offering speeds close to 3G technology, hence the name 2.75G. EDGE is standardized by the 3GPP as part of the GSM family and as an upgrade to GPRS.

EDGE was deployed on GSM networks beginning in 2003 – initially by Cingular (now AT&T) in the United States. It could be readily deployed on existing GSM and GPRS cellular equipment, making it an easier upgrade for cellular companies compared to the UMTS 3G technology that required significant changes. Through the introduction of sophisticated methods of coding and transmitting data, EDGE delivers higher bit-rates per radio channel, resulting in a threefold increase in capacity and performance compared with an ordinary GSM/GPRS connection - originally a max speed of 384 kbit/s. Later, Evolved EDGE was developed as an enhanced standard providing even more reduced latency and more than double performance, with a peak bit-rate of up to 1 Mbit/s.

Digital AMPS (D-AMPS), most often referred to as TDMA, is a second-generation (2G) cellular phone system that was once prevalent throughout the Americas, particularly in the United States and Canada since the first commercial network was deployed in 1993. Former large D-AMPS networks included those of AT&T and Rogers Wireless. The name TDMA is based on the abbreviation for time-division multiple access, a common multiple access technique which is used in most 2G standards, including GSM. D-AMPS competed against GSM and systems based on code-division multiple access (CDMA). It is now considered end-of-life, as existing networks have shut and been replaced by GSM/GPRS or CDMA2000 technologies. The last carrier to operate a D-AMPS network was U.S. Cellular, who terminated it on February 10, 2009.

The technical names for D-AMPS are IS-54 and its successor IS-136. IS-54 was the first mobile communication system which had provision for security, and the first to employ time-division multiple access (TDMA) technology. IS-136 added a number of features to the original IS-54 specification, including text messaging (SMS), circuit switched data (CSD), and an improved compression protocol. SMS and CSD were both available as part of the GSM protocol, and IS-136 implemented them in a nearly identical fashion.

The 3rd Generation Partnership Project (3GPP) is an umbrella term for a number of standards organizations which develop protocols for mobile telecommunications. Its best known work is the development and maintenance of:

• GSM and related 2G, 2.5G, and 2.75G standards, including GPRS and EDGE
• UMTS and related 3G standards, including HSPA and HSPA+
• LTE and related 4G standards, including LTE Advanced and LTE Advanced Pro
• 5G NR and related 5G standards, including 5G-Advanced
• An evolved IP Multimedia Subsystem (IMS) developed in an access independent manner

3GPP is a consortium with seven national or regional telecommunication standards organizations as primary members ("organizational partners") and a variety of other organizations as associate members ("market representation partners"). The 3GPP organizes its work into three different streams: Radio Access Networks, Services and Systems Aspects, and Core Network and Terminals.