(GSM, originally "Groupe de travail Spéciale pour les services Mobiles") A standard for digital cellular communications (in the process of being) adopted by over 60 countries. The GSM standard is currently used in the 900 MHz and 1800 MHz bands.

In the USA trial systems akin to the related Digital Cellular System (DCS) 18000 have been set up in several metropolitan areas.

HSCSD is a proposed standard for circuit switched data communications over GSM.

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[IEEE spectrum August 1999, pp. 26].