The Short Message Service (SMS) was originally defined as part of the GSM series of standards in 1985 as a means of sending "short" (160 characters or less) messages, most often text messages, to and from GSM mobiles. Since then, support for the service has expanded to include alternative mobile standards such as ANSI CDMA networks and AMPS, satellite and landline networks.

The service makes use of a Service Centre, which acts as a store and forward centre for short messages. The Service Centre communicates with the Public Land Mobile Network (PLMN) or PSTN via Interworking and Gateway MSCs.