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Content for  TS 23.272  Word version:  19.0.0

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C.8 Registration of MME for SMS  $ Change history 

 

C.8  Registration of MME for SMS  p. 98

C.8.1  Request for registration  p. 98

An MME supporting SMS in MME that needs to perform a registration with HSS shall follow the following procedure to become registered by the HSS also for SMS.
The following sequence shows the request for registration with the HSS for SMS in MME.
Copy of original 3GPP image for 3GPP TS 23.272, Fig. C.8.1-1: MME registration for SMS
Figure C.8.1-1: MME registration for SMS
(⇒ copy of original 3GPP image)
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Step 1.
The UE initiates combined attach or combined TA/LA Update to an MME. A UE that only supports NB-IoT (see TS 23.401) may issue an EPS attach or TA Update instead of a combined attach or combined TA/LA Update.
Step 2.
The MME sends a Location Update Request (SMS in MME feature flag, MME address for MT-SMS routing, RegistrationForSMSRequest, "SMS-only" Indication) message to HSS. SMS in MME feature flag indicates that the MME is capable of SMS transfer without the need of establishing an SGs association with an MSC. The "SMS-only" Indication is included if it has been included in the request from the UE. The MME includes one of the following RegistrationForSMSRequest values based on the criteria shown in Table C.8.1-1.
Value Description
SMS in MME Required
  • MME does not support SGs; or
  • The MME can be configured to use this value when the UE indicates "SMS only" or when known that the subscription is "PS and SMS only".
(Note 1)
SMS in MME Not Preferred
  • The MME can be configured to use this value when the UE indicates "SMS only" or when known that the subscription is "PS and SMS only"
  • The MME can be configured to use this value when the UE does not indicate "SMS only" (i.e. requests CSFB) and the MME has no subscriber data yet (when MME is configured to use SGs for "SMS and PS only" subscription).
(Note 2)
No Preference for SMS in MME
  • The MME has no preference configured to use SMS in MME or SGs, but both options are available from MME perspective.
(Note 2)
Step 3.
If the HSS supports SMS in MME and the subscription includes SMS:
  1. if one or more of the following is true:
    • Network Access Mode is PS only; or
    • the MME indicates "SMS in MME Required";
    then the HSS shall register the MME for SMS;
  2. if the MME indicates "No Preference for SMS in MME" and Network Access Mode is not equal to PS only but one or more of the following are true:
    • the UE indicated "SMS-only";
    • the subscription is limited to PS domain services and SMS service via the CS and the PS domain ("PS and SMS only");
    then the HSS should register the MME for SMS;
  3. if the MME indicates "SMS in MME Not Preferred" and Network Access Mode is not equal to PS only then the HSS should not register the MME for SMS;
  4. otherwise the HSS shall not register the MME for SMS.
    If HSS registered the MME for SMS, the HSS stores the MME address for MT SMS.
Step 4.
If the HSS accepts to register the MME identity as an MSC identity for terminating SMS services then the HSS cancels the MSC/VLR registration from the HSS.
Step 5.
The HSS sends a Location Update Answer (indication whether the MME has been registered for SMS, subscription data including the Network Access Mode and "PS and SMS only" indications, SMS subscription data, MPS for Messaging indication, SMS in MME feature flag) message to MME.
If the HSS does not register the MME for SMS, it shall indicate that the MME has not been registered for SMS and not include any SMS subscription data.
SMS in MME feature flag indicates that the HSS is capable of supporting the SMS in MME feature.
The MME stores the returned data and checks the result of registering the MME for SMS.
If the registration for SMS was not accepted, the MME does following:
  1. For a PS-only subscription (i.e. the Network Access Mode in the subscription equals "PS-only"), the MME shall not establish any SGs association (no SMS services are provided to the UE).
  2. For a "PS and SMS only" subscription where SMS can be provided over CS (i.e. the Network Access Mode equals "PS+CS" and the subscription parameter "PS and SMS only" is set), the MME tries to establish SGs for SMS.
  3. For a PS and CS subscription where also other CS services are allowed (i.e. Network Access Mode equals "PS+CS" and the subscription parameter "PS and SMS only" is not set), the MME tries to establish SGs for SMS and other CS services.
If the registration for SMS was accepted:
  • The HSS uses the Insert Subscriber Data procedure to inform the MME of changes in MPS for Messaging indication.
  • The HSS sets Diameter priority and DSCP on responses on the S6a and S6c interfaces with values that are appropriate for MPS.
  • The SMS-GMSC obtains the MPS for Messaging indication in the Send Routing Information for SM from the HSS. If the MPS for Messaging indication is set (enabled), the SMS-GMSC sets the Diameter priority and DSCP for SMS messages to values that are appropriate for MPS.
  • MME and SMS-GMSC set the Diameter priority and DSCP for SMS messages on the SGd interface to values that are appropriate for MPS.
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C.8.2  Removal of registration of MME for SMS  p. 100

C.8.2.0  General  p. 100

The removal of the registration of MME for SMS is used by:
  • The HSS to inform the MME that the registration of MME for SMS is cancelled; or by
  • The MME to inform the HSS that it requests to remove its registration for SMS.

C.8.2.1  HSS-initiated removal of registration of MME for SMS  p. 100

When the HSS needs to indicate to the MME that it is no longer registered for SMS, (e.g. because of a removal of SMS subscription, CS location update, etc), the following procedure is applied.
Copy of original 3GPP image for 3GPP TS 23.272, Fig. C.8.2-1: Cancellation of MME registration for SMS in MME
Figure C.8.2-1: Cancellation of MME registration for SMS in MME
(⇒ copy of original 3GPP image)
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Step 1.
There is an event that shall trigger the cancellation of the MME being registered for SMS. This may for example be the removal of the SMS subscription for the UE, a CS location update, etc.
Step 2.
The HSS sends an Insert Subscriber Data Request (Remove SMS registration) message to the MME to inform the MME that it is no more registered for SMS in MME.
Step 3.
The MME sets its "MME Registered for SMS" parameter as not registered for SMS and the "SMS subscription data" is considered by the MME as invalid. It acknowledges with an Insert Subscriber Data Answer message to the HSS.
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C.8.2.2  MME-initiated removal of registration of MME for SMS  p. 101

When the MME needs to indicate to the HSS that it is no longer registered for SMS in HSS, (e.g. because the UE initiated a EPS attach only, TAU), the following procedure is applied.
Copy of original 3GPP image for 3GPP TS 23.272, Fig. C.8.2-2: Removal of MME registration for SMS in HSS
Figure C.8.2-2: Removal of MME registration for SMS in HSS
(⇒ copy of original 3GPP image)
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Step 1.
There is an event that triggers the cancellation of the MME being registered for SMS. This may for example be an UE initiated EPS attach only or a TAU.
Step 2.
The MME sends a message to the HSS to inform the HSS to remove its registration for SMS in HSS.
Step 3.
The HSS cancels the SMS registration for the UE in the MME. It acknowledges and responds to the MME.

$  Change history  p. 102

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