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Customized Applications for Mobile networks Enhanced Logic
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<h2 id="camel-entities">CAMEL entities</h2> <ul><li>GSM Service Control Function (gsmSCF)</li> <li>GSM Service Switching Function (gsmSSF)</li> <li>GSM Specialized Resource Function (gsmSRF)</li> <li>GPRS Service Switching Function (gprsSSF)</li></ul> <h2 id="specifications">Specifications</h2> <p>CAMEL specification were published in phases,<a class="footnote-ref" id="fnref:1" href="#fn:1"><sup>1</sup></a> with four phases having been established As of 2007<a href="https://en.wikipedia.org/w/index.php?title=Customized_Applications_for_Mobile_networks_Enhanced_Logic&action=edit">[update]</a>, each building on the previous.<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a> Phases 1 and 2 were defined before <a href="/facts/3G/K1noBd8n">3G</a> networks existed, and as such support adding IN services to a <a href="/facts/Global_System_for_Mobile_Communications/Sw8QYaLE">GSM</a> network, although they are equally applicable to 2.5G and 3G networks. Phase 3 was defined for <a href="/facts/3GPP/TBrQYKFF">3GPP</a> Releases 99 and 4, and hence is a GSM and <a href="/facts/Universal_Mobile_Telecommunications_System/lhy2RrMw">UMTS</a> common specification, while Phase 4 was defined as part of 3GPP Release 5. </p><p>In line with other GSM specifications, later phases should be fully backwards compatible with earlier phases; this is achieved by means of the <a href="/facts/Transaction_Capabilities_Application_Part/AFMSBzUR">Transaction Capabilities Application Part</a> (TCAP) Application Context (AC) negotiation procedure, with each CAMEL phase is allocated its own AC version.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a> </p> <h3>Phase 1</h3> <p>CAMEL Phase 1 defined only very basic call control services, but introduced the concept of a CAMEL <a href="/facts/Basic_call_state_model/2WKxsy4e">Basic call state model</a> (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.<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> </p><p>Phase 1 was defined as part of Release 96 in 1997. </p> <h3>Phase 2</h3> <p>CAMEL Phase 2 enhanced the capabilities defined in Phase 1. In addition to supporting the facilities of Phase 1, Phase 2 included the following: </p> <ul><li>Additional event detection points</li> <li>Interaction between a user and a service using announcements, voice prompting and information collection via in-band interaction or <a href="/facts/Unstructured_Supplementary_Service_Data/2ACw7CYY">Unstructured Supplementary Service Data (USSD)</a> interaction</li> <li>Control of call duration and transfer of Advice of Charge Information to the mobile station;</li> <li>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)</li> <li>The ability, for easier post-processing, of integrating charging information from a serving node in normal call records<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a></li></ul> <p>Phase 2 was defined as part of <a href="/facts/3GPP/TBrQYKFF">3GPP</a> Releases 97 and 98, in 1998, although it is referenced in the stage 1 specification of Release 96. </p> <h3>Phase 3</h3> <p>The third phase of CAMEL enhanced the capabilities of phase 2. The following capabilities were added: </p> <ul><li>Support of facilities to avoid overload</li> <li>Capabilities to support Dialed Services</li> <li>Capabilities to handle mobility events, such as (Not-)reachability and roaming;</li> <li>Control of GPRS sessions and PDP contexts</li> <li>Control of Mobile Originated <a href="/facts/Short_message_service/kacRfW0X">SMS</a> through both circuit-switched and packet-switched serving network entities</li> <li>Interworking with SoLSA (Support of Localised Service Area). Support for this interworking is optional;</li> <li>The gsmSCF can be informed about the invocation of the supplementary service Call Completion to Busy Subscriber (CCBS)<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a></li></ul> <p>Phase 3 was released as part of 3GPP Releases 99 and 4 in 1999. </p> <h3>Phase 4</h3> <p>The fourth phase of CAMEL built on the capabilities of phase 3. The following features were defined: </p> <ul><li>Support for Optimal Routing of circuit-switched mobile-to-mobile calls</li> <li>The capability for the gsmSCF to create additional parties in an existing call (Call Party Handling)</li> <li>The capability for the gsmSCF to create a new call unrelated to any other existing call (Call Party Handling - new call)</li> <li>Capabilities for the enhanced handling of call party connections (Call Party Handling)</li> <li>Control of Mobile Terminated <a href="/facts/Short_message_service/kacRfW0X">SMS</a> through both circuit-switched and packet-switched serving network entities</li> <li>The capability for the gsmSCF to control sessions in the <a href="/facts/IP_Multimedia_Subsystem/9Wmc57pL">IP Multimedia Subsystem (IMS)</a><a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a></li> <li>The gsmSCF can request the gsmSSF to play a fixed or a variable sequence of tones</li></ul> <p>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. </p><p>Phase 4 was released as part of <a href="/facts/3GPP/TBrQYKFF">3GPP</a> Release 5 in 2002. </p> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/Open_Services_Architecture/uGkj2wDm">Open Services Architecture</a></li> <li><a href="/facts/IP_Multimedia_Subsystem/9Wmc57pL">IP Multimedia Subsystem</a></li> <li><a href="/facts/Service_layer/JPBlfdIH">Service layer</a></li> <li><a href="/facts/Camel/UGvEayFf">Camel</a></li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>3GPP TS 02.78 Release 96 specification for the service aspects of CAMEL Phase 1 & 2 (zip file). <a href="http://www.3gpp.org/ftp/Specs/archive/02_series/02.78/0278-560.zip" target="_blank">http://www.3gpp.org/ftp/Specs/archive/02_series/02.78/0278-560.zip</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>3GPP TS 22.078 Release 5 specification for CAMEL phase 4 (zip file). <a href="http://www.3gpp.org/ftp/Specs/archive/22_series/22.078/22078-5f0.zip" target="_blank">http://www.3gpp.org/ftp/Specs/archive/22_series/22.078/22078-5f0.zip</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>3GPP TS 29.078 CAMEL Application Part specification for Release 5 (zipped Word document). <a href="http://www.3gpp.org/ftp/Specs/archive/29_series/29.078/29078-590.zip" target="_blank">http://www.3gpp.org/ftp/Specs/archive/29_series/29.078/29078-590.zip</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>3GPP TS 02.78 Release 96 specification for the service aspects of CAMEL Phase 1 & 2 (zip file). <a href="http://www.3gpp.org/ftp/Specs/archive/02_series/02.78/0278-560.zip" target="_blank">http://www.3gpp.org/ftp/Specs/archive/02_series/02.78/0278-560.zip</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>3GPP TS 02.78 Release 96 specification for the service aspects of CAMEL Phase 1 & 2 (zip file). <a href="http://www.3gpp.org/ftp/Specs/archive/02_series/02.78/0278-560.zip" target="_blank">http://www.3gpp.org/ftp/Specs/archive/02_series/02.78/0278-560.zip</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>3GPP TS 22.078 Release 5 specification for CAMEL phase 4 (zip file). <a href="http://www.3gpp.org/ftp/Specs/archive/22_series/22.078/22078-5f0.zip" target="_blank">http://www.3gpp.org/ftp/Specs/archive/22_series/22.078/22078-5f0.zip</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>3GPP TS 22.078 Release 5 specification for CAMEL phase 4 (zip file). <a href="http://www.3gpp.org/ftp/Specs/archive/22_series/22.078/22078-5f0.zip" target="_blank">http://www.3gpp.org/ftp/Specs/archive/22_series/22.078/22078-5f0.zip</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> </ol>