Position of the SMS System in the GSM Network

Position of the SMS System in the GSM

The position of the SMSC in the GSM network. The physical entities related to the SMSC are the MSC, VLR and the HLR. Their functions in the SM transmission are as follows:

• MSC
  
  • The SMs submitted by the MS pass the BSS and reach the MSC. Then the MSC forwards them to the corresponding SMSC.
    
  • After receiving the SMs delivered by the SMSC, the MSC queries the VLR and the HLR for the related routing and subscriber information, and then delivers them to subscribers through BSS.
    
    
• VLR
  The VLR stores the temporary information of a subscriber roaming in the local MSC area. The subscriber must pass the authentication through the VLR before sending an SM, and the MSC queries the route of a subscriber through the VLR before delivering an SM.
  
  
• HLR
  The HLR is a database for mobile subscriber management. It stores the subscription information, position information, mobile station international ISDN number (MSISDN), and international mobile station identity (IMSI) of a subscriber. Before delivering SM, the SMSC finds which MSC the subscriber belongs to through the HLR.