GSM - Global System for Mobile

[Derrick]

GSM is a second generation digital mobile cellular technology using a combination of frequency division multiple access (FDMA) and time division multiple access (TDMA). GSM operates in several frequency bands: 400 MHz, 900 MHz and 1800 MHz. On the TDMA side, there are eight timeslots or channels carrying calls, which operate on the same frequency. Unlike other cellular systems, GSM provides a high degree of security by using subscriber identity module (SIM) cards and GSM encryption.

Source: http://telkom.investoreports.com/telkom_ar_2010/admin/definitions/