Overview

2G refers to the second generation of cellular systems introduced as a replacement for the first-generation analog networks. It moved mobile services from analog to digital transmission, improving capacity, call quality and enabling new services for mobile phone users. The term covers several incompatible air interfaces and regional standards across operators and countries, and is commonly described as a technology family rather than a single specification.

Characteristics

Core features of 2G networks include circuit-switched voice, subscriber identity modules (SIM cards), short message service (SMS) and basic encryption of over-the-air traffic. Data rates were low by modern standards; packet-based upgrades later provided modest internet access. 2G prioritized efficient use of radio spectrum and wider geographic coverage compared with 1G analog systems.

Major standards

  • GSM (Global System for Mobile communications) — the dominant system in Europe, Africa and many parts of Asia.
  • IS-95 (cdmaOne) — a CDMA-based 2G variant deployed in parts of the Americas and Asia.
  • D-AMPS and other regional flavors — derivatives that evolved from the basic 2G concepts.

These standards differ in how they divide radio resources and manage calls, but all share the move away from analog transmission and toward digital signaling (GSM, IS-95).

History and evolution

Introduced in the early 1990s, 2G networks enabled services that were impractical on 1G, most notably SMS and international roaming. Subsequent enhancements such as GPRS and EDGE offered higher data throughput and are often called 2.5G or 2.75G. Over time, operators deployed 3G (3G) and later 4G/LTE to provide broadband mobile internet, but 2G remained widely used for voice and simple data for many years.

Uses, legacy and transitions

Even after newer generations arrived, 2G retained importance for basic voice calls, text messaging and low-bandwidth Internet of Things (IoT) devices thanks to its wide coverage and low power requirements. Many carriers have shut down or are retiring 2G networks to reassign spectrum to faster systems, a transition that affects legacy devices and some M2M applications. The phase-out highlights trade-offs between freeing capacity for modern mobile broadband and preserving service for older hardware.

Notable facts and considerations

2G introduced ubiquitous features now taken for granted—SIM cards, global SMS and standardized roaming—but it also had limitations: modest data speeds and cryptographic protections that are weaker than later generations. Those security and capacity limits are among the reasons operators have migrated customers to more advanced networks while supporting targeted legacy needs during the transition.