11.3.9 Short Message Service (SMS)

3GPP43.068Release 17Stage 2TSVoice Group Call Service (VGCS)

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

11.3.9.1 Delivering SMS to the voice group call

If the talking service subscriber, the listening service subscriber, the dispatcher in a voice group call, or any initiator of short messages who is not part of the voice group call wants to send a short message to the voice group call, it shall use the numbering scheme based on ITU‑T Recommendation E.164 as the destination address illustrated below.

NDC

Prefix

Group call reference

The Country Code (CC) and National Destination Code (NDC) are used as normal for routing purposes. The CC and NDC may be omitted for internal SMS. The Subscriber Number (SN) is used to indicate:

– the request of an SMS to a voice group call by use of a prefix. The length of the prefix shall be 1 to 2 digits. The value of the prefix shall be the same as the value used by a dispatcher when originating the voice group call (see subclause 9.2 d);

– the wanted group call reference as defined in subclause 9.1.

When receiving the short message, the SC may send Delivery Report message containing the received group call reference of the voice group to the sender of the short message, and furthermore the SC shall attempt to deliver the short message to the voice group call addressed by the group call reference. Figure 7k shows the MT SMS delivery procedure.

Figure 7k: Successful MT short message transfer attempt to a voice group call

1) The SC sends a Message Transfer message to forward a short message to the SMS-GMSC.

2) The SMS-GMSC sends the MT_ForwardSM_For_VGCS_REQ message to transfer the received short message to the anchor MSC using the routing information derived from the group call reference.

3) The anchor MSC sends the GCR_SMS_Interrogation message to the GCR to retrieve the voice group call attributes for short message transfer.

4) The GCR sends the GCR_SMS_Interrogation_Res message to the anchor MSC containing the voice group call status and optionally the list of identities of dispatchers.
In RANflex configuration with Group Call redundancy message 4 may indicate that the group call is ongoing at another anchor MSC within the redundancy pool. If so, message 2 is relayed to that anchor MSC (not shown in figure 7k).

5) The anchor MSC sends the MT_ForwardSM_For_VGCS_RES message to the SMS-GMSC containing the status of the voice group call and optionally a list of identities of dispatchers if received from the GCR. Optionally, if the voice group call is currently ongoing, the SMS-GMSC may initiate point to point short message transfer attempts to the dispatchers of the voice group call.

6) If the voice group call is established, the anchor MSC sends the FORWARD_GROUP CALL_SIGNALLING message to deliver the short message to all related relay MSCs in the voice group call.

7) If the voice group call is established, the anchor MSC sends Message Transfer message to deliver the short message to the MSs participating in the voice group call within its MSC area.

8) If the voice group call is established, the relay MSCs sends Message Transfer message to deliver the short message to the MSs participating in the voice group call within its MSC area.

11.3.9.2 Point-to-point short message during an ongoing voice group call

In this subclause the term point-to-point short message is used for mobile terminating short messages destined to a single subscriber and for mobile originating short messages, regardless whether their final destination is a single subscriber or a voice group call.

For the transmission and reception of point-to-point short messages via CS domain during an ongoing voice group call, an MS and a network supporting this functionality shall apply the procedures specified in 3GPP TS 23.040 [14] and 3GPP TS 24.011 [15] as follows:

a) When the talking service subscriber is on a dedicated channel, point-to-point short messages to be sent or received via the CS domain shall be transmitted on the SACCH of the dedicated channel. If the talking service subscriber requests to release the uplink while a short message transfer is ongoing, the MS shall initiate the release of the uplink and abort the transfer of the short message.

b) When the talking service subscriber is on a voice group call channel, the MS shall send mobile originating short messages via the CS domain on the SACCH of the voice group call channel, if at least one of the following conditions is fulfilled:

– the short message is destined to the ongoing voice group call of the talker;

– the network broadcasts neither an SMS data confidentiality indication nor an SMS guaranteed privacy indication on the NCH; or

– the network broadcasts an SMS data confidentiality indication, but no SMS guaranteed privacy indication on the NCH, and the voice group call channel is ciphered.

Otherwise the MS shall leave the voice group call, send the short message as specified in 3GPP TS 24.011 [15] and return to the group call in group receive mode afterwards, if possible.

If the talking service subscriber requests to release the uplink while a short message transfer on the voice group call channel is ongoing, the MS shall initiate the release of the uplink and abort the transfer of the short message.

c) When the talking service subscriber is on a voice group call channel, the network may deliver mobile terminating point-to-point short messages via the CS domain on the SACCH of the voice group call channel, if at least one of the following conditions is fulfilled:

– the network does not broadcast an SMS data confidentiality indication on the NCH; or

– the network broadcasts an SMS data confidentiality indication on the NCH, and the voice group call channel is ciphered.

Otherwise the network shall perform paging into the ongoing voice group call as described in subclause 11.3.1.3 c. The paging information on the FACCH of the voice group call channel shall indicate explicitly that the paging is for a short message. When the paging is received in group transmit mode, the reception of the paging shall be indicated to the subscriber. It is then up to the subscriber to respond to the paging or not. On request of the subscriber to respond to the paging, the MS in group transmit mode shall release the uplink, leave the voice group call, receive the short message as specified in 3GPP TS 24.011 [15], and return to the group call in group receive mode afterwards, if possible.

d) If an MS on a voice group call channel is not the endpoint of the layer 2 link for acknowledged message transfer, it shall ignore point-to-point short messages received on the SACCH of the voice group call channel.

e) On request of a listening service subscriber to send a point-to-point short message, the MS in group receive mode shall leave the voice group call, send the short message as specified in 3GPP TS 24.011 [15], and return to the group call in group receive mode afterwards, if possible.

For the delivery of a point-to-point short message to a listening service subscriber, the network shall peform paging into ongoing voice group calls by means of the notification procedure as described in subclause 11.3.1.3. The notification messages on the FACCH of the voice group call channel shall indicate explicitly that the paging is for a short message. When the paging is received in group receive mode, the reception of the paging shall be indicated to the subscriber. It is then up to the subscriber to respond to the paging or not. On request of the subscriber to respond to the paging, the MS in group receive mode shall leave the voice group call, receive the short message as specified in 3GPP TS 24.011 [15], and return to the group call in group receive mode afterwards, if possible.

For the transmission and reception of point-to-point short messages via PS domain during an ongoing voice group call, class A mobile stations supporting this functionality shall apply the procedures specified in 3GPP TS 23.040 [14] and 3GPP TS 24.011 [15].

Editor’s note: For DTM mobile stations the transmission and reception of point-to-point short messages via PS domain during an ongoing voice group call is ffs.