The GSM standard originally described a digital, circuit-switched network optimized for full duplex voice telephony.

Nevertheless, as a result of the network's widespread use, the acronym "GSM" is still used as a generic term for the plethora of G mobile phone technologies evolved from it.

In 1983, work began to develop a European standard for digital cellular voice telecommunications when the European Conference of Postal and Telecommunications Administrations (CEPT) set up the Groupe Spécial Mobile (GSM) committee and later provided a permanent technical-support group based in Paris.

Five years later, in 1987, 15 representatives from 13 European countries signed a memorandum of understanding in Copenhagen to develop and deploy a common cellular telephone system across Europe, and EU rules were passed to make GSM a mandatory standard.

[6] The decision to develop a continental standard eventually resulted in a unified, open, standard-based network which was larger than that in the United States.

The MoU drew in mobile operators from across Europe to pledge to invest in new GSM networks to an ambitious common date.

In this short 38-week period the whole of Europe (countries and industries) had been brought behind GSM in a rare unity and speed guided by four public officials: Armin Silberhorn (Germany), Stephen Temple (UK), Philippe Dupuis (France), and Renzo Failli (Italy).

[11] In 1989 the Groupe Spécial Mobile committee was transferred from CEPT to the European Telecommunications Standards Institute (ETSI).

It was long believed that the former Finnish prime minister Harri Holkeri made the world's first GSM call on 1 July 1991, calling Kaarina Suonio (deputy mayor of the city of Tampere) using a network built by Nokia and Siemens and operated by Radiolinja.

[13] In 2021 a former Nokia engineer Pekka Lonka revealed to Helsingin Sanomat making a test call just a couple of hours earlier.

In 2002, the first Multimedia Messaging Service (MMS) was introduced and the first GSM network in the 800 MHz frequency band became operational.

(High Speed Packet Access (HSPA) and its uplink and downlink versions are 3G technologies, not part of GSM.)

The common standard reduced research and development costs, since hardware and software could be sold with only minor adaptations for the local market.

Picocells are typically deployed when significant call capacity is needed indoors, as in shopping centers or airports.

However, this is not a prerequisite, since indoor coverage is also provided by in-building penetration of radio signals from any nearby cell.

In rare cases the 400 and 450 MHz frequency bands are assigned in some countries because they were previously used for first-generation systems.

In some countries and regions (e.g. Brazil and Germany) all phones are sold unlocked due to the abundance of dual-SIM handsets and operators.

[27] Research findings indicate that GSM faces susceptibility to hacking by script kiddies, a term referring to inexperienced individuals utilizing readily available hardware and software.

The vulnerability arises from the accessibility of tools such as a DVB-T TV tuner, posing a threat to both mobile and network users.

Despite the term "script kiddies" implying a lack of sophisticated skills, the consequences of their attacks on GSM can be severe, impacting the functionality of cellular networks.

Given that GSM continues to be the main source of cellular technology in numerous countries, its susceptibility to potential threats from malicious attacks is one that needs to be addressed.

[32] GSM uses General Packet Radio Service (GPRS) for data transmissions like browsing the web.

They also noted that some carriers do not encrypt the data (i.e., using GEA/0) in order to detect the use of traffic or protocols they do not like (e.g., Skype), leaving customers unprotected.

If used with USIM to prevent connections to fake base stations and downgrade attacks, users will be protected in the medium term, though migration to 128-bit GEA/4 is still recommended.

[34][35][36] The GSM systems and services are described in a set of standards governed by ETSI, where a full list is maintained.

[37] Several open-source software projects exist that provide certain GSM features:[38] Patents remain a problem for any open-source GSM implementation, because it is not possible for GNU or any other free software distributor to guarantee immunity from all lawsuits by the patent holders against the users.