CAP (CAMEL Application Part)

CAMEL Application Part is the SS7 protocol that lets a service control point trigger and influence calls in real time, enabling prepaid charging, virtual private networks, and other intelligent network services in 2G and 3G. CAP runs on top of TCAP and is functionally similar to INAP. Because it can authorise or extend calls, malicious or misconfigured CAP messages can enable revenue leakage and toll fraud, so CAP traffic is filtered alongside MAP at the SS7 firewall.

Categories: SignalingIdentity and SubscriberSecurity Controls

CAP in context

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.

Subscriber identifiers (IMSI, SUPI, MSISDN, IMEI) are the anchor for authentication, charging, lawful interception and fraud analytics. Any protocol or interface that leaks a permanent identifier is treated as a serious privacy defect, which is why 5G introduced SUCI concealment on the air interface.

To place CAP in the wider telecom-security picture, review Any-Time Interrogation (ATI), IMSI, Roaming, Control Plane Security, Ingress and OCS.

Related terms

Related topic hubs

  • SS7 Security SS7/MAP/CAP/SCCP attacks and defenses across 2G/3G interconnect.
  • SS7 Firewall GSMA FS.11 category 1/2/3 SS7 message screening at the STP edge.
  • Signaling Firewall Unified SS7/Diameter/GTP/SMS signaling firewall framework.
  • Telecom Fraud IRSF, Wangiri, SIM box, PBX hacking and CLI spoofing.

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