GMSC (Gateway Mobile Switching Center)

GMSC in context

The mobile core is where subscriber sessions, mobility and policy live. 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. Core exposure is the difference between a single-subscriber leak and a fleet-wide breach.

Roaming and interconnect are where two operators, often with an IPX or GRX carrier in between, exchange signaling and user-plane traffic. Trust boundaries here are the primary attack surface for location tracking, SMS interception and fraud, which is why GSMA now mandates SEPP with PRINS on 5G interconnect.

To place GMSC in the wider telecom-security picture, review GSMA, GGSN, HLR, PGW, GMLC and Cryptography.

Related terms

• GSMA
• GGSN
• HLR
• PGW
• GMLC
• Cryptography
• GTP Firewall
• iSIM

Equipment

Circuit-switched core (MSC, MSC-S, VLR, GMSC, MGW)

• CSFB
• Media Gateway
• MGCF
• MSC
• VLR

Articles in the P1 mobile network security guide

Related topic hubs

• Roaming Security IPX/GRX interconnect risk, home-routed vs local-breakout, SEPP.
• VoLTE Security IMS/VoLTE signaling risk: SIP, IMS-AKA, media plane attacks.
• IMS Security Training Training on IMS, VoLTE/VoNR, SIP and RCS security.
• Diameter Security 4G/LTE Diameter threats across IPX/roaming and DEA defenses.

More from the TelcoSec Glossary

Browse the full TelcoSec Glossary, the Ultimate Guide to Mobile Network Security, or the P1 Arsenal of telecom-security tools.