4.2 Information Flows

23.0943GPPFollow-Me (FM)Release 17Stage 2TS

4.2.1 Information Flow for the handling of FM by the initiating subscriber

Figure 4.1 shows the Information Flow for the control of FM (registration, erasure, forced erasure and interrogation) by the initiating subscriber.

For any control operation on FM, the initiating subscriber (MSa) enters a Follow Me Request (FM-Request). This is a USSD string containing the requested FM operation and the remote number. The Follow Me Request is routed via the MSC/VLR to the HLR of the initiating subscriber (HLRa).

The HLRa performs a series of checks as described in the SDLs (clause 4.3). If these checks fail, the MSa receives a response (FM-Response) indicating the error.

If the checks pass, the HLRa forwards the operation request (HLR-FM-Request) to the FFN of the remote party (FFNb).

FFNb carries out the appropriate control operation and checks as described in the SDLs (clause 4.3) for the remote party.

The result of this operation (success or error) is reported back in a USSD Response to the initiating subscriber.

For successful forced erasure by a service supervisor, the FFN shall send a Network Initiated USSD notify message with the corresponding USSD string to the HLR of the previously registered subscriber who had registered the Follow Me data. The HLR shall forward the USSD notify to VLR which will relay the USSD Notify towards the MS.

Upon receipt of the USSD Notify, the MS shall respond by sending a FACILITY message with empty return result component.

An error response with corresponding reason can be returned from any entity, when error happens at the entity 3GPP TS 23.090 [8].

Figure 4.1: Information flow for the control of FM by the initiating subscriber or service supervisor

NOTE 1: OR1:N: The case where the checks in the HLR result in a negative outcome, e.g. FM is not provisioned for the initiating subscriber or the initiating subscriber is not allowed to operate FM for the remote party.

OR1:Y: The case where all the checks in the HLR are successful, e.g. FM is provisioned for the initiating subscriber and the initiating subscriber is allowed to operate FM for the remote party.

NOTE 2: […] Optional parameter.

(…)] Conditional parameter.

OC Operation Code (Register, Erase or Interrogate).

SC Service Code for FM.

RN Remote Number.

SI Supervisor Indicator. This parameter is conditional and only used for forced erasure by a FM service supervisor.

PIM MSISDN of previously registered subscriber who has registered the FM to remote number. This parameter is conditional and only used for forced erasure by a FM service supervisor..

AI Supplementary Information containing additional information.

MSISDN-A initiating number in international format. It is not a part of the USSD string, but is sent from HLRa to the FFNb together with the HLR-FM-Request within the MAP operation. For forced erasure, the MSISDN-A corresponds to the supervisor’s MSISDN and will be part of the USSD-notify.

MSp MS of previously registered service subscriber.

HLRp HLR of the previously registered service subscriber.

4.2.2 Information Flow for the handling of FM by the remote party

Control of FM by the remote party is possible if the remote party is a GSM subscriber.

The information flow for control of FM by the remote party (erasure and interrogation of her own FM data) is the same as the information flow for control of FM by the initiating subscriber.

If a remote party tries to register FM to herself the registration is rejected and an error is reported.