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SMS Network Architecture and Key Elements

sms gsm network architecture mobile communication short message service

This article covers the following aspects of SMS:

  • SMS basics and types
  • SMS network and elements
  • SMS MO (Mobile Originated) and MT (Mobile Terminated) call flow
  • SMS versus MMS

SMS Network Elements

The SMS network in GSM is composed of the following network elements:

  • SMSC (Short Message Service Center)
  • HLR (Home Location Register)
  • MSC (Mobile Switching Center)
  • VLR (Visitor Location Register)
  • BSC (Base Station Controller)
  • BTS (Base Transceiver Station)
  • MS (Mobile Station) or UE (User Equipment)

SMS Transmission

SMS messages are carried by the signaling channel (specifically, SDCCH - Standalone Dedicated Control Channel) on the air interface between the MS and the BTS. From there, the SMS is transported using the SS7 signaling protocol through the BSC, MSC/VLR, and finally to the SMSC.