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 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.

Roaming and interconnect are where two operators 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 Cryptography, GMSC, GSMA, AKA, AUSF and Behavioral Signaling Detection — each entry cross-references back to this page so you can walk the topic in either direction.

Related terms

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.