CAMEL Application Part

The CAMEL Application Part (CAP) is a signalling protocol used in the intelligent network architecture. It is part of the SS7 protocol suite layered on top of the Transaction Capabilities Application Part (TCAP) or Digital Subscriber Signalling System No. 1 (DSS1). CAP is based on a subset of the ETSI Core INAP CS-2 protocol.

Protocol specification

As with CAMEL, CAP has been defined in 4 phases, each of which has an accompanying specification that builds upon the previous phase. Each CAP phase provides the message set and procedures needed to support the corresponding CAMEL phase requirements, as defined in 3GPP TS 22.078 (service aspects) and 3GPP TS 23.078 (technical realization).

The definition of the protocol may be considered to be split into 3 sections:

• the definition of the Single Association Control Function (SACF)/Multiple Association Control Function (MACF) rules for the protocol, defined within the prose of the specification;
• the definition of the operations transferred between entities, defined using Abstract Syntax Notation One (ASN.1);
• the definition of the actions taken at each entity, defined by means of state transition diagrams.