Content for  TS 23.078  Word version:  19.0.0

Assisting case involves the following processes:

• CAMEL_Assisting_MSC,
• Assisting_gsmSSF.

The detailed error handling for these 2 processes is specified in TS 29.078.

The procedure CAMEL_Provide_Subscriber_Info is called either during Retrieval of routeing information in the HLR or as a result of reception of the Any Time Interrogation information flow from the gsmSCF. The HLR sends a Provide Subscriber Info information flow to the VLR or SGSN dependent on the setting of the parameter "requested domain" received from the calling process. If the VLR or SGSN returns a Provide Subscriber Info ack information flow, then the HLR uses the received information to set the Subscriber Info to be returned to the calling process. As a network option, the HLR may use the information received from the VLR, such as Cell Id, Location Area Id or Service Area Id, to derive the Location Number and/or Geographical Information. The HLR may use the information received from the SGSN, such as Cell Id, Location Area Id, Service Area Id or Routeing Area Identity, to derive the Location Number and/or Geographical Information. This mapping is network-specific and outside the scope of the present document.

When requesting a location update or data restoration the VLR shall indicate to the HLR which CAMEL phases it supports and which CAMEL phase 4 CSIs can be downloaded. The HLR may then send CAMEL subscription data to the VLR or, if some different handling is required, data for substitute handling. The CAMEL subscription data sent by the HLR shall comply with the indication of supported CAMEL phases and supported CAMEL phase 4 CSIs as received from the VLR. When the location update has been completed, the MSC/VLR in which the subscriber is registered after the location update shall check the M-CSI. If a Mobility Management notification to the gsmSCF is required for this subscriber, then the MSC/VLR shall send the notification to the gsmSCF. Refer to subclause 9.2.1 for a description of M-CSI and the conditions under which a notification shall be sent.

To avoid a case by case fallback between the gsmSSF and the gsmSCF, the gsmSSF shall use the CAP phase corresponding to the CAMEL phase negotiated on the HLR-VLR interface when it opens a dialogue with the gsmSCF. The HLR-VLR negotiation of CAMEL phase is per subscriber.

The following procedures apply only when the HPLMN of the CAMEL subscriber and either the VPLMN (for a mobile originated or forwarded call) or the IPLMN (for a mobile terminated call or forwarded call) are both North American. A gsmSCF may then provide the gsmSSF with any of the following North American (NA) carrier related information items.

• NA Carrier Information;
• NA Originating Line Information;
• NA Charge Number.

A gsmSSF shall use the received information items both to select any long distance carrier needed for the call and to provide certain information needed by this carrier. Any required information items not received shall be defaulted to those that would normally apply to the call in the absence of an interaction with a gsmSCF. If any NA information item received from the gsmSCF is found to be invalid, the gsmSSF may either, as an operator option, release the call or behave as if the invalid information item had not been sent. If the carrier specified in the Carrier parameter is not supported in the VPLMN or IPLMN, the gsmSSF may either, as an operator option, release the call or substitute for the unsupported carrier a preferred carrier of the VPLMN or IPLMN. Support of the NA Originating Line Information and Charge Number parameters is an operator option in a VPLMN based on roaming agreements with the operators of other PLMNs, A gsmSSF may ignore these items when received from certain or all gsmSCFs located in other PLMNs and replace them with the corresponding default items for an MO, MF, MT or VT call.

The handling of trunk originated calls in the inter-connecting MSC is specified in subclause 7.5 of TS 23.018. The processes and procedures specific to CAMEL are specified in this subclause.

• Procedure CAMEL_TOC_Dialled_Services;
• Procedure CAMEL_TOC_MSC_INIT;
• Procedure CAMEL_NDS_TOC_INIT;
• Procedure CAMEL_TOC_LEG1_MSC.

The procedure CAMEL_TOC_LEG1_MSC supervises the originating party only. The process CAMEL_MT_CF_LEG2_MSC supervises the called-to party only. Hence, signals from the originating exchange are received by the procedure CAMEL_TOC_LEG1_MSC and signals from the destination exchange are received by the process CAMEL_MT_CF_LEG2_MSC.