CAMEL entities
*GSM Service Control Function (gsmSCF) *GSM Service Switching Function (gsmSSF) *GSM Specialized Resource Function (gsmSRF) *GPRS Service Switching Function (gprsSSF)Specifications
CAMEL specification were published in phases,3GPP TS 02.78Phase 1
CAMEL Phase 1 defined only very basic call control services, but introduced the concept of a CAMEL Basic call state model (BCSM) to the Intelligent Network (IN). Phase 1 gave the gsmSCF the ability to bar calls (release the call prior to connection), allow a call to continue unchanged, or to modify a limited number of call parameters before allowing it to continue. The gsmSCF could also monitor the status of a call for certain events (call connection and disconnection), and take appropriate action on being informed of the event. Phase 1 was defined as part of Release 96 in 1997.Phase 2
CAMEL Phase 2 enhanced the capabilities defined in Phase 1. In addition to supporting the facilities of Phase 1, Phase 2 included the following: * Additional event detection points * Interaction between a user and a service using announcements, voice prompting and information collection via in-band interaction or Unstructured Supplementary Service Data (USSD) interaction * Control of call duration and transfer of Advice of Charge Information to the mobile station; * The ability to inform the gsmSCF about the invocation of the supplementary services Explicit Call Transfer (ECT), Call Deflection (CD) and Multi-Party Calls (MPTY) * The ability, for easier post-processing, of integrating charging information from a serving node in normal call records Phase 2 was defined as part of 3GPP Releases 97 and 98, in 1998, although it is referenced in the stage 1 specification of Release 96.Phase 3
The third phase of CAMEL enhanced the capabilities of phase 2. The following capabilities were added: * Support of facilities to avoid overload * Capabilities to support Dialed Services * Capabilities to handle mobility events, such as (Not-)reachability and roaming; * Control of GPRS sessions and PDP contexts * Control of Mobile Originated SMS through both circuit-switched and packet-switched serving network entities * Interworking with SoLSA (Support of Localised Service Area). Support for this interworking is optional; * The gsmSCF can be informed about the invocation of the supplementary service Call Completion to Busy Subscriber (CCBS) Phase 3 was released as part of 3GPP Releases 99 and 4 in 1999.Phase 4
The fourth phase of CAMEL built on the capabilities of phase 3. The following features were defined: * Support for Optimal Routing of circuit-switched mobile-to-mobile calls * The capability for the gsmSCF to create additional parties in an existing call (Call Party Handling) * The capability for the gsmSCF to create a new call unrelated to any other existing call (Call Party Handling - new call) * Capabilities for the enhanced handling of call party connections (Call Party Handling) * Control of Mobile Terminated SMS through both circuit-switched and packet-switched serving network entities * The capability for the gsmSCF to control sessions in the IP Multimedia Subsystem (IMS) * The gsmSCF can request the gsmSSF to play a fixed or a variable sequence of tones With CAMEL Phase 4, it is possible that only a limited subset of the new functionalities is supported, in addition to the complete support of CAMEL Phase 3. Phase 4 was released as part of 3GPP Release 5 in 2002.See also
* Open Services Architecture * IP Multimedia Subsystem * Service layer * CamelReferences
{{Reflist, 2 Signaling System 7 GSM standard