The SCS/AS sends an Enhanced Coverage Request (External Identifier or MSISDN, SCS/AS Identifier, Request Type, Enhanced Coverage Restriction Data, MTC Provider Information) message to the SCEF. Request Type indicates if the request is to query the status of, or to enable, or to disable the enhanced coverage restriction. Enhanced Coverage Restriction Data provides data related to the Enhanced Coverage Restriction. Enhanced Coverage Restriction Data is only present if Request Type is to either enable or disable the enhanced coverage restriction.
The SCEF stores the SCS/AS Identifier. The SCEF assigns an SCEF Reference ID. Based on operator policies, if either the SCS/AS is not authorized to perform this request (e.g. if the SLA does not allow for it) or the Enhanced Coverage Request is malformed or the SCS/AS has exceeded its quota or rate of submitting Enhanced Coverage requests, the SCEF performs step 9 and provides a Cause value appropriately indicating the failure result.
The HSS examines the Enhanced Coverage Request message, e.g. with regard to the existence of External Identifier or MSISDN, whether any included parameters are in the range acceptable for the operator, whether the Enhanced Coverage restriction is supported by the serving MME/SGSN. If this check fails the HSS follows step 8 and provides a Cause value indicating the reason for the failure condition to the SCEF.
If the Request Type is to get the current status of enhanced coverage HSS retrieves the value and procedure follows at Step 8. Else If the Type is to enable or to disable the enhanced coverage, HSS sets Enhanced Coverage Restricted parameter to the appropriate value and the procedure continues at step 5.
If required by the specific Enhanced Coverage Request Type and when Enhanced Coverage is supported by the serving MME/SGSN, the HSS sends an Insert Subscriber Data Request (Type, SCEF ID, SCEF Reference ID) message to the MME/SGSN.
Based on operator policies, the MME/SGSN may reject the request (e.g. overload or HSS has exceeded its quota or rate of submitting enhanced coverage requests defined by an SLA).
The MME/SGSN updates Enhanced Coverage Restricted parameters in the MME/SGSN context.
The MME/SGSN will transfer the Enhanced Coverage Restricted parameters stored as part of its context information during MME/SGSN change.
If the Enhanced Coverage restriction is updated successful, the MME/SGSN sends an Insert Subscriber Data Answer (Cause) message to the HSS. MME/SGSN may include the Enhanced Coverage Restricted parameter in the Insert Subscriber Data Answer message.
The HSS sends an Enhanced Coverage Response (SCEF Reference ID, Cause) message to the SCEF. HSS includes result = success/failure and in the case of success may include Enhanced Coverage Restriction Data.
In the case of UE mobility, the HSS determines whether the new MME/SGSN supports Enhanced Coverage restriction.
The SCEF sends an Enhanced Coverage Response (Cause, Enhanced Coverage Restriction Data) message to the SCS/AS. Cause indicates success or failure. If in step 1 the Enhanced Coverage Request message is sent to query the status of Enhanced Coverage Restricted, then Enhanced Coverage Restriction Data is included (in the case of success) in the Enhanced Coverage Response message.