Three primary benefits of 2G networks over their predecessors were:
Digitally encrypted phone conversations, at least between the mobile phone and the cellular base station but not necessarily in the rest of the network.
Data services for mobile, starting with SMS text messages.
2G technologies enabled the various networks to provide services such as text messages, picture messages, and MMS (multimedia messages).
After 2G was launched, the previous mobile wireless network systems were retroactively dubbed 1G. While radio signals on 1G networks are analog, radio signals on 2G networks are digital. Both systems use digital signaling to connect the radio towers (which listen to the devices) to the rest of the mobile system.
With General Packet Radio Service (GPRS), 2G offers a theoretical maximum transfer speed of 40 kbit/s (5 kB/s).[2] With EDGE (Enhanced Data Rates for GSM Evolution), there is a theoretical maximum transfer speed of 384 kbit/s (48 kB/s).[2]
The most common 2G technology was the time-division multiple access (TDMA)-based GSM, originally from Europe but used in most of the world outside Japan and North America. In North America, Digital AMPS (IS-54 and IS-136) and cdmaOne (IS-95) were the main systems. In Japan, the ubiquitously deployed system was Personal Digital Cellular (PDC), and another one called Personal Handy-phone System (PHS) also existed.
Evolution
Cellular network standards and generation timeline.
2.5G ("second and a half generation"[3]) is used to describe 2G-systems that have implemented a packet-switched domain in addition to the circuit-switched domain. It doesn't necessarily provide faster service because bundling of timeslots is used for circuit-switched data services (HSCSD) as well.
GPRS networks evolved to EDGE networks with the introduction of 8PSK encoding. While the symbol rate remained the same at 270.833 samples per second, each symbol carried three bits instead of one. Enhanced Data rates for GSM Evolution (EDGE), Enhanced GPRS (EGPRS), or IMT Single Carrier (IMT-SC) is a backward-compatible digital mobile phone technology that allows improved data transmission rates, as an extension on top of standard GSM. EDGE was deployed on GSM networks beginning in 2003, initially by AT&T in the United States.
2G, understood as GSM and CDMA, has been superseded by newer technologies such as 3G (UMTS / CDMA2000), 4G (LTE / WiMAX) and 5G (5G NR); however, 2G networks are still used in most parts of Europe, Africa, Central America and South America,[4][5][6] and many modern LTE-enabled devices are known to still fallback to 2G for phone calls, especially in rural areas.[7] In some places, its successor 3G is being shut down rather than 2G – Vodafone previously announced that it had switched off 3G across Europe in 2020 but still retains 2G as a fallback service.[8] Meanwhile, in the US, T-Mobile plans to shut down their 3G prior to their 2G GSM network being shut down.[9][10]
Various carriers have made announcements that 2G technology in the United States, Japan, Australia, and other countries are in the process of being shut down, or have already shut down 2G services so that carriers can reclaim those radio bands and re-purpose them for newer technologies (e.g. 4G, 5G).[11][12]
In 2022, Android 12 introduced a system setting to disable 2G connectivity for the device, supposedly to mitigate security concerns associated with 2G networks.[13]
Criticism
In some parts of the world, including the United Kingdom, 2G remains widely used for feature phones and for internet of things (IoT) devices where the high patent licensing cost of newer technologies makes them prohibitive, such as smart meters, eCall systems and vehicle tracking devices.[14][8][15] Terminating 2G services could leave vulnerable people who rely on 2G infrastructure without means to access emergency contacts, leading to preventable deaths.[15]
Shutdown of CDMA transmitters began in remote areas in 2017, followed by an official announcement in June 2018 that 2G devices will lose service soon.[23][24]
As of December 2020 network coverage almost completely vanished with remote sites remaining that do not emit a 3G signal in order to preserve CSFB functionality.[57][58][59]
