What is the frequncey in which 2gmobile oprate?

Frequency is the number of times per second at which an electromagnetic wave oscillates. It determines the wave's properties and usage. Frequencies are measured in hertz (Hz). 1 Hz is one oscillation per second, 1 kHz a thousand, 1 MHz is a million and 1GHz is a thousand million. Frequencies between 30 kHz and 300 GHz are widely used for telecommunication, including broadcast radio and television, and comprise the radio frequency band. Mobile telephony systems currently operate at 900MHz, 1800MHz and 2100MHz. GSM - Global System for Mobile Communications or Groupe Speciale Mobile is the international, pan-European operating standard for the current generation of digital cellular mobile communications. It enables mobile phones to be used across national boundaries. GSM systems are operated by O2 and Vodafone at 900 and 1800 MHz, and by T-Mobile and Orange at 1800MHz.