ETSI - TS 123 078
Digital cellular telecommunications system (Phase 2+) (GSM); Universal Mobile Telecommunications System (UMTS); Customised Applications for Mobile network Enhanced Logic (CAMEL) Phase 4; Stage 2
|Publication Date:||1 April 2022|
The present document specifies the stage 2 description for the fourth phase (see 3GPP TS 22.078 ) of the Customized Applications for Mobile network Enhanced Logic (CAMEL) feature which provides the mechanisms to support services of operators which are not covered by standardized services even when roaming outside the HPLMN.
The CAMEL feature is a network feature and not a supplementary service. It is a tool to help the network operator to provide the subscribers with the operator specific services even when roaming outside the HPLMN.
In the present document, the GSM Service Control Function (gsmSCF) is treated as being part of the HPLMN. The regulatory environment in some countries may require the possibility that the gsmSCF and the HPLMN are controlled by different operators, and the gsmSCF and the HPLMN are therefore distinct entities.
The fourth phase of the CAMEL feature supports, in addition to the third phase of the CAMEL:
- Interactions with Optimal Routing;
- Call Party Handling;
- DTMF Mid call procedure for Mobile Originated and Mobile Terminating calls;
- Inclusion of flexible tone injection;
- Provision of location information of called subscriber;
- Provide location information during ongoing call;
- CAMEL control over MT SMS;
- Notification of GPRS mobility management to CSE;
- Inclusion of ODB data in Any Time Modification;
- Enhancement of Any Time Interrogation and Provide Subscriber Information for PS Domain;
- Mobile Number Portability database interrogation;
- Criteria for the provision of location information during ongoing call;
- Enhanced Dialled Services;
- Enhancement to Establish Temporary Connection;
- CAMEL control of trunk originated calls.
CAMEL applicability to IP-based multimedia services is introduced in the fourth phase of the CAMEL. It is specified in 3GPP TS 23.278 .
CAMEL is not applicable to Emergency Setup (TS 12), i.e. if an Emergency call is requested, then the gsmSSF shall not be invoked.
The mechanism described in the present document addresses especially the need for information exchange between the VPLMN or IPLMN and the HPLMN for support of operator specific services. Any user procedures for the control of operator specific services are outside the scope of the present document. Subscribers who have subscribed to operator specific services and therefore need the functional support of the CAMEL feature shall be marked in the HPLMN and VPLMN. In case a subscriber is marked to need CAMEL support, the appropriate procedures which provide the necessary information to the VPLMN or the HPLMN are invoked. It is possible for the HPLMN to instruct the VPLMN or IPLMN to interact with a gsmSCF which is controlled by the HPLMN.
The specification of operator specific services is outside the scope of the present document.
Support of partial implementation of CAMEL phase 4
A functional entity (VMSC, GMSC or SGSN) may support the complete CAMEL phase 4 functionality or, as a network option, it may support the complete CAMEL phase 3 functionality and a partial implementation of CAMEL phase 4.
If a functional entity supports any part of CAMEL phase 4, then the HLR is informed of the CAMEL phase 4 CSIs supported. An SGSN may also indicate support of the Provide Subscriber Information IF. To indicate support of a specific CSI, a functional entity shall have the ability to trigger on any initial service event possible for that CSI.
If a VMSC or GMSC supports any of the CAMEL phase 4 circuit switched CSIs (O-CSI, D-CSI, T-CSI or VT-CSI), then the gsmSCF is informed of the CAMEL phase 4 circuit switched functionalities offered. The gsmSCF shall not send information flows or parameters that conflict with the functionalities offered by the VMSC or GMSC.
If a CAMEL subscriber attempts to register in a VMSC or SGSN which supports at least one CAMEL phase 4 CSI or the enhancement of Provide Subscriber Information IF, then the VMSC or SGSN indicates in the registration request to the HLR the phase of CAMEL which the VMSC or SGSN supports (at least phase 4). In addition, the VMSC or SGSN indicates which CAMEL phase 4 CSIs may be downloaded. An SGSN may also indicate support of the Provide Subscriber Information IF.
If a GMSC supports at least one CAMEL phase 4 CSI, then the GMSC indicates in the Send Routeing Info to the HLR the phase of CAMEL which the GMSC supports (at least phase 4). In addition, the GMSC indicates which CAMEL phase 4 CSIs may be downloaded.
If a VMSC/gsmSSF or GMSC/gsmSSF initiates contact with the gsmSCF using the Initial DP IF, or acknowledges a gsmSCF initiated contact using the Initiate Call Attempt ack IF, then the VMSC/gsmSSF or GMSC/gsmSSF indicates in the IF the CAMEL phase 4 functionalities offered to the gsmSCF.
If a VLR initiates contact with the gsmSCF using a Mobility Management Event Notification IF, then the VLR or SGSN indicates in the IF the functionalities offered to the gsmSCF.
CAMEL Phase 4 CSIs
A network entity may indicate to the HLR an offer of support for the following CAMEL phase 4 CSIs:
- CAMEL phase 4 O-CSI;
- CAMEL phase 4 D-CSI;
- CAMEL phase 4 T-CSI;
- CAMEL phase 4 VT-CSI;
- CAMEL phase 4 MT-SMS-CSI;
- CAMEL phase 4 MG-CSI;
CAMEL control of trunk originated calls;
- Reporting of additional dialled digits.
An SGSN may also indicate support of the CAMEL phase 4 Provide Subscriber Information IF.
A functional entity (VMSC, GMSC or SGSN) may offer the CSIs in any combination applicable for this entity. A functional entity shall indicate to the HLR all the CSIs it offers. The HLR may ignore the offer of the supported CSIs if they are not applicable for the sending entity, but it shall not reject the operation in this case.
CAMEL Phase 4 Functionalities
The CAMEL phase 4 functionalities which may be offered to the gsmSCF are the following:
- Creating additional parties in a call, Creating a new call (Initiate Call Attempt);
- Placing an individual call party on hold or moving an individual call party to Call Segment 1, when Call Segment 1 does not exist (Split Leg);
- Connecting an individual call party to the group (Move Leg);
- Releasing an individual call party (Disconnect Leg);
- Indication of the release of a call party or call segment (Entity Released);
- Enhancements for subscriber interactions with the gsmSCF (Disconnect Forward Connection With Argument);
- Inclusion of flexible tone injection (Play Tone);
- DTMF Mid call procedure for MO and VT calls (DP O_Mid_Call, DP T_Mid_Call);
- Provision of Charge Indicator at answer DP (Charge Indicator at DP O_Answer, DP T_Answer);
- Support of Alerting DP (DP O_Term_Seized, DP Call_Accepted);
- Provision of location information of subscriber at alerting DP (Location information at DP O_Term_Seized, DP Call_Accepted);
- Provision of location information during an ongoing call (DP O_Change_Of_Position
- Interactions with Basic Optimal Routeing (Basic OR Interrogation Requested in Connect and Continue With Argument, Route Not Permitted in DP O_Abandon);
- Warning tone enhancements (Burstlist for Audible Indicator);
- Enhancements of Call Forwarding indication (Forwarding Destination Number);
- Criteria for the provision of location information during ongoing call (Criteria for DP O_Change_Of_Position
- Subscribed Enhanced Dialled services (see description below);
- Serving Network Enhanced Dialled Services (see description below);
- SCUDIF notification during active phase of the call (DP O_Service_Change and T_Service_Change) ; and
Collection of additional dialled digits (Arming CollectedInfo DP as EDP-R).
For the Subscribed Enhanced Dialled Services and Serving Network Enhanced Dialled Services, the following information flows apply in addition to the information flows allowed at TDP Analysed_Information
A functional entity (VMSC or GMSC) may offer the functionalities in any combination applicable for this entity and applicable to the offered CSIs.
A functional entity (VMSC or GMSC) shall indicate to the gsmSCF all the functionallities it offers.