During the early 1980s, analog cellular telephone systems were experiencing rapid growth in Europe, particularly in Scandinavia and the United Kingdom, but also in France and Germany. Each country developed its own system, which was incompatible with everyone else's in equipment and operation. This was an undesirable situation, because not only was the mobile equipment limited to operation within national boundaries, which goes against a unified Europe, but there was also a very limited market for each type of equipment to achieve economies of scale and the subsequent savings could not be realized.

The Europeans realized this early on, and in 1982 the Conference of European Posts and Telegraphs (CEPT) formed a study group called the Groupe Spécial Mobile (GSM) to study and develop a pan-European public land mobile system. The proposed system had to meet certain criteria:

• Good subjective speech quality
• Low terminal and service cost
• Support for international roaming
• Ability to support handheld terminals
• Support for range of new services and facilities
• Spectral efficiency
• ISDN compatibility

In 1989, GSM responsibility was transferred to the European Telecommunication Standards Institute (ETSI), and phase I of the GSM specifications were published in 1990. Commercial service was started in mid-1991, and by 1993 there were 36 GSM networks in 22 countries. Although standardized in Europe, GSM is not only a European standard. Over 200 GSM networks (including DCS1800 and PCS1900) are operational in 110 countries around the world. In the beginning of 1994, there were 1.3 million subscribers worldwide (Europe, Asia), which had grown to more than 55 million by October 1997. With North America making a delayed entry into the GSM field with a derivative of GSM called PCS1900, GSM systems had already exist on every other continent.  Beginning with Voicestream/TMobile/Rogers and now AT&T, Cingular joining the ranks; we begin to experience the advantages of one global standard of phones.  The acronym GSM now aptly stands for Global System for Mobile communications.   With the introduction of Pay-As-You-Go chips or disposal GSM SIMs in some countries, you can imagine the advantages of a GSM phone today.  You can pay local charges and say goodbye to phone booths or pay phones while you travel.   If you understand the purpose of GSM, you will quickly realized that locking a phone is all a brilliant marketing plan to retain customers within a carrier. This will however limit the use of GSM and the recycling of phones.  To remove this limitation is to unlock your phone.