PCRF (Policy and Charging Rules Function)

The Policy and Charging Rules Function is the 4G LTE element that decides QoS, gating and charging rules for each subscriber session. It pushes them to the PGW's policy enforcement point over the Diameter Gx interface, and talks to the IMS over Rx for VoLTE bearer authorization. The PCRF is the 4G predecessor of the 5G Policy Control Function (PCF), and its interfaces carry subscriber and session data that must be protected on the management and signalling planes.

Categories: Core NetworkOperations and BusinessSignaling

PCRF 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.

OSS/BSS platforms (provisioning, charging, mediation, order management) hold the highest-value subscriber and revenue data on the operator side. They are heavily targeted for fraud and insider abuse and are increasingly in scope for regulatory obligations like NIS2 and the UK Telecoms Security Act.

To place PCRF in the wider telecom-security picture, review PCF, PGW, Rx Interface, Diameter, PDN and CSCF.

Related terms

Equipment

Policy and charging (PCRF, PCF, CHF, OCS, OFCS)

Articles in the P1 mobile network security guide

Related topic hubs

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.