SMS Home Routing

SMS Home Routing is the GSMA-recommended deployment in which all incoming SMS for a roaming subscriber is routed back through the home operator's SMS Home Router rather than delivered directly via the visited SMSC. The Home Router answers the SRI-SM query with a single non-routable address, hiding the subscriber's IMSI and current location from the foreign SMSC. It is one of the most effective controls against SS7-based location tracking and OTP interception.

Categories: Core NetworkSignalingRoaming and Interconnect

SMS Home Routing in context

The mobile core carries subscriber sessions, mobility and policy. In 4G it is the EPC (MME, HSS, S/PGW); in 5G it is the Service-Based Architecture with AMF, SMF, UPF, AUSF, UDM and the NRF.

Signaling protocols carry the control-plane messages that set up calls, register subscribers and route SMS. SS7, Diameter, GTP-C and SIP are the four dominant families, and interconnect exposure of any of them is treated by GSMA as top-tier telecom risk.

To place SMS Home Routing in the wider telecom-security picture, review HLR, MAP Security, MAP, Signaling Penetration Testing, GTP-C and SGSN: each entry cross-references back to this page so you can walk the topic in either direction.

Related terms

Related topic hubs

  • Signaling Firewall Unified SS7/Diameter/GTP/SMS signaling firewall framework.
  • SMS Firewall SMS spam, phishing, A2P bypass and MAP-layer SMS filtering.
  • Roaming Security IPX/GRX interconnect risk, home-routed vs local-breakout, SEPP.
  • SS7 Security SS7/MAP/CAP/SCCP attacks and defenses across 2G/3G interconnect.

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