GSM Services

• GSM service through the GSM network enable subscribers to make calls via different provider services and to roam in different countries. Roaming refers to network connectivity in an area not included in the provider's service region.
  
  

Outgoing Calls

• Outgoing GSM calls are initiated when the user dials a telephone number and presses the talk or send key on his mobile phone. The phone transmits a call setup request via the cell tower in closest vicinity to the user, which sends a signal to the mobile phone network. The mobile phone network, also known as the GSM core network, handles the call switching functions through the network of cell towers.
  
  

Incoming Calls

• An individual places a GSM call to a mobile phone by dialing the telephone number associated with that mobile phone. The call is routed to the appropriate operator's Gateway MSC, or Gateway Mobile Switching Center. This switching center enables the outside caller on the Public Switched Telephone Network to connect to the mobile phone user's private network.