Subscriber

A subscriber is a customer with an active service contract on a telecom network, identified by an IMSI/SUPI on the SIM and reachable via an MSISDN. Operators manage subscribers in the HLR/HSS/UDM and apply per-subscription policies for QoS, roaming, charging, and lawful interception. Subscriber data is highly sensitive personal information and a frequent target of data-protection regulation.

Categories: Core NetworkRoaming and InterconnectIdentity and Subscriber

Subscriber 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 Subscriber in the wider telecom-security picture, review HLR, PDN, PGW, SIMBox Fraud, SRI and UPF.

Related terms

Related topic hubs

  • Roaming Security IPX/GRX interconnect risk, home-routed vs local-breakout, SEPP.
  • 5G Security 5G SBA, SEPP, SUCI, 5G-AKA, N32 and service-based interface security.
  • VoLTE Security IMS/VoLTE signaling risk: SIP, IMS-AKA, media plane attacks.
  • IMS Security Training Training on IMS, VoLTE/VoNR, SIP and RCS security.

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.