IMS (IP Multimedia Subsystem)

IMS in context

The radio access network is the layer where mobile devices attach to the operator's infrastructure. Attacks in this layer include IMSI catching, rogue base stations, downgrade attacks and jamming, and defenses hinge on mutual authentication, integrity-protected signaling and Open RAN supply-chain hygiene.

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.

To place IMS in the wider telecom-security picture, review CSCF, Mobile Network, TEID, GSM, Interconnection and LTE.

Related terms

• CSCF
• Mobile Network
• TEID
• GSM
• Interconnection
• LTE
• Provide Subscriber Information (PSI)
• Service-Based Architecture (SBA) Security

Equipment

IMS core (CSCF, TAS, MRF, MGCF, BGCF)

• BGCF
• CSCF
• E-CSCF
• I-CSCF
• IMS-AKA
• IR.92
• IR.94
• MGCF
• MTSI
• P-CSCF
• All 14 terms

Articles in the P1 mobile network security guide

Related topic hubs

• VoLTE Security IMS/VoLTE signaling risk: SIP, IMS-AKA, media plane attacks.
• IMS Security Training Training on IMS, VoLTE/VoNR, SIP and RCS security.
• SS7 Security SS7/MAP/CAP/SCCP attacks and defenses across 2G/3G interconnect.
• 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.