OFCS (Offline Charging System)

OFCS 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.

Signaling protocols carry the control-plane instructions that set up calls, register subscribers, hand over sessions and route SMS. SS7, Diameter, GTP-C and SIP are the four dominant families, and interconnect exposure of any of them is treated by GSMA FS.11 / FS.19 / FS.20 as a top-tier telecom risk.

To place OFCS in the wider telecom-security picture, review OCS, AAA, UMTS, GTP-C Spoofing, Rogue Base Station (Fake BTS) and Zeek.

Related terms

• OCS
• AAA
• UMTS
• GTP-C Spoofing
• Rogue Base Station (Fake BTS)
• Zeek
• BTS Impersonation (Fake BTS)
• CAP

Equipment

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

• Charging System
• CHF
• OCS
• PCF
• PCRF

Articles in the P1 mobile network security guide

Related topic hubs

• Signaling Firewall Unified SS7/Diameter/GTP/SMS signaling firewall framework.
• SS7 Firewall GSMA FS.11 category 1/2/3 SS7 message screening at the STP edge.
• Diameter Security 4G/LTE Diameter threats across IPX/roaming and DEA defenses.
• Diameter Firewall GSMA FS.19 screening at the Diameter Edge Agent on S6a/S9/S13.

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.