Signal & Syntax · Networks, HLR and porting

What Is SRI-SM?

SRI-SM (Send Routing Info for Short Message) is the MAP query an SMSC sends the HLR. The HLR replies with the serving switch.

Also calledSend Routing Info for Short Message · SRI for SM

SRI-SM in Practice

The SMSC asks the HLR where the destination number is being served. The HLR returns the IMSI and the serving switch address, or an error. An absent-subscriber error means the handset is off or out of coverage. HLR lookup services send the same operation without sending an SMS.

Related Terms

MSISDN MSISDN stands for Mobile Station International Subscriber Directory Number. HLR The HLR (Home Location Register) is the subscriber database in a mobile operator's core network. SMSC An SMSC (Short Message Service Center) stores and forwards SMS. IMSI The IMSI (International Mobile Subscriber Identity) is the up-to-15-digit code on a SIM.

Read the Guide

Guide

HLR Lookup vs eHLR

Two ways to check whether a number is in use. Read the guide →

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