10.19 Ad hoc group call
23.3793GPPFunctional architecture and information flows to support Mission Critical Push To Talk (MCPTT)Release 18Stage 2TS
10.19.1 General
This subclause contains procedures for ad hoc group call across a single MCPTT system, and associated functions such as emergency call, Imminent peril call, broadcast call and others.
The ad hoc group calls can use the participants list provided by either an initiator of the call or MCPTT server. The MCPTT server can use the criteria provided by the initiator of the call to determine the participants list along with its own criteria or local policies. The resulting ad hoc group uses the configuration of a separate preconfigured MCPTT group.
NOTE 1: A preconfigured group which is intended only to provide configuration for the ad hoc group is identified by a parameter in the group configuration described in 3GPP TS 23.280 [16].
The preconfigured MCPTT group that provides the configuration is not used for the MCPTT group communication, it only provides configuration for one or more adhoc group calls. The MCPTT group ID of the ad hoc group call is provided by the MCPTT server when the ad hoc group call is originated. In order to establish security context for the end-to-end secured ad hoc group call, the security related information is used from this preconfigured group.
NOTE 2: The configurations defined for the adhoc group call in user profile and service configuration document as described in the Annex A.3 and A.5 is applicable only for single MCPTT system.
Editor’s note: The configurations required for supporting adhoc group call involving multiple MCPTT system is FFS.
10.19.2 Information flows
10.19.2.1 Ad hoc group call request (MCPTT client – MCPTT server)
Table 10.19.2.1-1 describes the information flow ad hoc group call request from the MCPTT client to the MCPTT server.
Table 10.19.2.1-1 Ad hoc group call request information elements
|
Information Element |
Status |
Description |
|
MCPTT ID |
M |
The MCPTT ID of the calling party |
|
Functional alias |
O |
The functional alias of the calling party |
|
MC service ad hoc group ID (see NOTE 1) |
O |
The MC service group ID which is generated by the MC service user to be associated with the ad hoc group communication |
|
Encryption supported (see NOTE 2) |
O |
Indicates whether this ad hoc group call supports end-to-end encryption |
|
MCPTT ID list (see NOTE 3, NOTE 6) |
O |
MCPTT IDs of the participants being invited for the ad hoc group call |
|
SDP offer |
M |
Media parameters of MCPTT clients |
|
Implicit floor request (see NOTE 4) |
O |
When originating client requests the floor, this element shall be included |
|
Broadcast indicator (see NOTE 5) |
O |
Indicates that the group call request is for a broadcast group call |
|
Imminent peril indicator (see NOTE 5) |
O |
Indicates that the ad hoc group call request is an MC service imminent peril call |
|
Emergency Indicator (see NOTE 5) |
O |
Indicates that the ad hoc group call request is an MC service emergency call |
|
MCPTT ID list (see NOTE 3) |
O |
List of participants required to acknowledge the ad hoc group call before start of the audio transmission |
|
Location information |
O |
Location of the calling party. |
|
Criteria for determining the participants (see NOTE 6) |
O |
Carries the details of criteria or meaningful label identifying the criteria or the combination of both which will be used by the MCPTT server for determining the participants e.g., it can be a location based criteria to invite particpants in a particular area |
|
Requested priority |
O |
Application priority level requested for this group call |
|
NOTE 1: If this information element is not included, the MC service server assigns an MC service ad hoc group ID to be used for the ad hoc group communication. This information element is returned to the calling party to use in the ad hoc group communication. NOTE 2: This information element is present and set to true only if this ad hoc group call is encrypted. When the ad hoc group call is initiated with participants provided by the initiator this acts as an indicator that subsequent requests follow targeting the individual participants and carrying the relevant key material. If this information element is set to false or not present, then this ad hoc group call is unencrypted. NOTE 3: This element is included only when the originating client sends the list of participants. NOTE 4: This element is included only when the originating client requests the floor. NOTE 5: If used, only one of these information elements is present. NOTE 6: Only one of these information elements is present. |
||
10.19.2.2 Ad hoc group call request return (MCPTT server – MCPTT client)
Table 10.19.2.2-1 describes the information flow ad hoc group call request return from the MCPTT server to the MCPTT client. This response could be intermediate response to provide the server assigned MCPTT ad hoc group ID.
Table 10.19.2.2-1 Ad hoc group call request return information elements
|
Information Element |
Status |
Description |
|
MCPTT ID |
M |
The MCPTT ID of the calling party |
|
MCPTT ad hoc group ID |
O |
The MCPTT group ID to be associated with the ad hoc group call which is assigned by the MCPTT server.This information element shall be present if the authorization result is success. |
|
Authorization result |
M |
Indicate if authorization is success or failure |
10.19.2.3 Ad hoc group call request (MCPTT server – MCPTT server)
Table 10.19.2.3-1 describes the information flow ad hoc group call request between the MCPTT servers.
Table 10.19.2.3-1 Ad hoc group call request information elements
|
Information Element |
Status |
Description |
|
MCPTT ID |
M |
The MCPTT ID of the calling party |
|
Functional alias |
O |
The functional alias of the calling party |
|
MCPTT ad hoc group ID |
M |
The MCPTT group ID to be associated with the ad hoc group call |
|
MCPTT ID list (see NOTE 1, NOTE 3) |
O |
MCPTT IDs of the participants being invited for the ad hoc group call |
|
SDP offer |
M |
Media parameters of MCPTT server |
|
Broadcast indicator (see NOTE 2) |
O |
Indicates that the ad hoc group call request is for a broadcast ad hoc group call |
|
Imminent peril indicator (see NOTE 2) |
O |
Indicates that the ad hoc group call request is an MC service imminent peril call |
|
Emergency Indicator (see NOTE 2) |
O |
Indicates that the ad hoc group call request is an MC service emergency call |
|
Preconfigured ad hoc group identity |
O |
Group identity whose configuration is to be applied for this ad hoc group call. |
|
Criteria for determining the participants (see NOTE 3) |
O |
Carries the details of criteria or meaningful label identifying the criteria or the combination of both which will be used by the MCPTT server for determining the participants e.g., it can be a location based criteria to invite particpants in a particular area |
|
Requested priority |
O |
Application priority level requested for this group call |
|
NOTE 1: This element is included only when the originating client sends the list of participants. NOTE 2: If used, only one of these information elements is present. NOTE 3: Only one of these information elements is present. |
||
10.19.2.4 Ad hoc group call request (MCPTT server – MCPTT client)
Table 10.19.2.4-1 describes the information flow ad hoc group call request from the MCPTT server to the MCPTT client.
Table 10.19.2.4-1 Ad hoc group call request information elements
|
Information Element |
Status |
Description |
|
MCPTT ID |
M |
The MCPTT ID of the calling party |
|
Functional alias |
O |
The functional alias of the calling party |
|
MCPTT ad hoc group ID |
M |
The MCPTT group ID to be associated with the ad hoc group call |
|
SDP offer |
M |
Media parameters of MCPTT server |
|
Broadcast indicator (see NOTE 1) |
O |
Indicates that the ad hoc group call request is for a broadcast ad hoc group call |
|
Imminent peril indicator (see NOTE 1) |
O |
Indicates that the ad hoc group call request is an MC service imminent peril call |
|
Emergency Indicator (see NOTE 1) |
O |
Indicates that the ad hoc group call request is an MC service emergency call |
|
Preconfigured ad hoc group identity |
O |
Group identity whose configuration is to be applied for this ad hoc group call. |
|
NOTE 1: If used, only one of these information elements is present. |
||
10.19.2.5 Ad hoc group call response (MCPTT server – MCPTT client)
Table 10.19.2.5-1 describes the information flow ad hoc group call response from the MCPTT server to the MCPTT client.
Table 10.19.2.5-1 Ad hoc group call response information elements
|
Information Element |
Status |
Description |
|
MCPTT ID |
M |
The MCPTT ID of the calling party |
|
Functional alias |
O |
The functional alias of the calling party |
|
MCPTT group ID |
M |
The MCPTT group ID to be associated with the ad hoc group call |
|
SDP answer |
O |
Media parameters selected and present if the Result is success. |
|
Result |
M |
Result of the group call request (success or failure) |
10.19.2.6 Ad hoc group call response (MCPTT server – MCPTT server)
Table 10.19.2.6-1 describes the information flow ad hoc group call response between the MCPTT servers.
Table 10.19.2.6-1 Ad hoc group call response information elements
|
Information Element |
Status |
Description |
|
MCPTT ID |
M |
The MCPTT ID of the target MC service user |
|
Functional alias |
O |
The functional alias of the target MC service user |
|
MCPTT ad hoc group ID |
M |
The MCPTT group ID to be associated with the ad hoc group call |
|
SDP answer |
O |
Media parameters selected and present if the Result is success. |
|
Result |
M |
Result of the ad hoc group call request (success or failure) |
10.19.2.7 Ad hoc group call response (MCPTT client – MCPTT server)
Table 10.19.2.7-1 describes the information flow ad hoc group call response from the MCPTT client to the MCPTT server.
Table 10.19.2.7-1 Ad hoc group call response information elements
|
Information Element |
Status |
Description |
|
MCPTT ID |
M |
The MCPTT ID of the target MC service user |
|
Functional alias |
O |
The functional alias of the target MC service user |
|
MCPTT ad hoc group ID |
M |
The MCPTT group ID to be associated with the ad hoc group call |
|
SDP answer |
O |
Media parameters selected and present if the Result is success. |
|
Result |
M |
Result of the ad hoc group call request (success or failure) |
10.19.2.8 Ad hoc group call release request (MCPTT server – MCPTT client)
Table 10.19.2.8-1 describes the information flow ad hoc group call release request from the MCPTT server to the MCPTT client.
Table 10.19.2.8-1 Ad hoc group call release request information elements
|
Information Element |
Status |
Description |
|
MCPTT ID |
M |
The MCPTT ID of the ad hoc group call participant |
|
Functional alias |
O |
The functional alias of the ad hoc group call participant |
|
MCPTT ad hoc group ID |
M |
The MCPTT group ID of the ad hoc group call on which call is released |
10.19.2.9 Ad hoc group call release response (MCPTT client – MCPTT server)
Table 10.19.2.9-1 describes the information flow ad hoc group call release response from the MCPTT server to the MCPTT client.
Table 10.19.2.9-1 Ad hoc group call release response information elements
|
Information Element |
Status |
Description |
|
MCPTT ID |
M |
The MCPTT ID of the ad hoc group call participant |
|
Functional alias |
O |
The functional alias of the ad hoc group call participant |
|
MCPTT group ID |
M |
The MCPTT group ID of the ad hoc group call on which call is released |
10.19.2.10 Ad hoc group call notify (MCPTT server – MCPTT client)
Table 10.19.2.10-1 describes the information flow ad hoc group call notify from MCPTT server to MCPTT client.
Table 10.19.2.10-1: Ad hoc group call notify
|
Information element |
Status |
Description |
|
MCPTT ID |
M |
The MCPTT ID of the calling party |
|
Functional alias |
O |
The functional alias of the calling party |
|
MCPTT ad hoc group ID |
M |
The MCPTT group ID associated with the ad hoc group call |
|
MCPTT ID list (see NOTE) |
O |
The list of the invited MC service users who did not acknowledge the ad hoc group call request |
|
NOTE: Only applicable to acknowledged group calls. |
||
10.19.2.11 Modify ad hoc group call participants request (MCPTT client – MCPTT server)
Table 10.19.2.11-1 describes the information flow Modify ad hoc group call participants request from the MCPTT client to the MCPTT server.
Table 10.19.2.11-1: Modify ad hoc group call participants request
|
Information element |
Status |
Description |
|
MCPTT ID |
M |
The MCPTT ID of the calling party |
|
Functional alias |
O |
The functional alias of the calling party |
|
MCPTT ad hoc group ID |
M |
The MCPTT group ID of ad hoc group call whose participants list needs to be modified |
|
MCPTT ID list (see NOTE) |
O |
List of additional MCPTT users to be added to the on-going ad hoc group call |
|
MCPTT ID list (see NOTE) |
O |
List of MCPTT users to be removed from the on-going ad hoc group call |
|
NOTE: Either one or both of these information elements is present |
||
10.19.2.12 Modify ad hoc group call participants response (MCPTT server – MCPTT client)
Table 10.19.2.12-1 describes the information flow Modify ad hoc group call participants response from the MCPTT server to the MCPTT client.
Table 10.19.2.12-1 Modify Ad hoc group call participants response information elements
|
Information Element |
Status |
Description |
|
MCPTT ID |
M |
The MCPTT ID of the calling party |
|
Functional alias |
O |
The functional alias of the calling party |
|
MCPTT ad hoc group ID |
M |
The MCPTT group ID of ad hoc group call whose participants list needs to be modified |
|
Result |
M |
Result of the modify ad hoc group call participants request (success of failure) |
|
MCPTT ID list |
O |
List of MCPTT users who are not allowed to be added to the on-going ad hoc group call. This list is provided if the operation is partially success. |
10.19.2.13 Ad hoc group call leave request (MCPTT server – MCPTT client)
Table 10.19.2.13-1 describes the information flow ad hoc group call leave request from the MCPTT server to the MCPTT client.
Table 10.19.2.13-1 Ad hoc group call leave request information elements
|
Information Element |
Status |
Description |
|
MCPTT ID |
M |
The MCPTT ID of the ad hoc group call participant leaving the call |
|
MCPTT ad hoc group ID |
M |
The MCPTT group ID of ad hoc group call on which call is on-going |
|
Reason to leave |
O |
Carries the reason of why the MCPTT client is being asked to leave the ongoing ad hoc group call |
10.19.2.14 Ad hoc group call leave response (MCPTT client – MCPTT server)
Table 10.19.2.14-1 describes the information flow Ad hoc group call leave response from the MCPTT client to the MCPTT server.
Table 10.19.2.14-1 Ad hoc group call leave response information elements
|
Information Element |
Status |
Description |
|
MCPTT ID |
M |
The MCPTT ID of the ad hoc group call participant leaving the call |
|
MCPTT ad hoc group ID |
M |
The MCPTT group ID of ad hoc group call on which call is on-going |
10.19.3.1 Ad hoc group call procedures in single MCPTT system
10.19.3.1.1 Ad hoc group call setup
Figure 10.19.3.1.1-1 below illustrates the ad hoc group call setup procedure initiated by an authorized user.
Pre-conditions:
1. The authorized user at MCPTT client 1 wants to invite MCPTT users at MCPTT client 2, MCPTT client 3 and MCPTT client 4 for the ad hoc group call.
2. Number of participants being invited for the ad hoc group call is within the limit for non pre-configured approach.
3. End-to-End encryption is supported for this ad hoc group call.
4. MCPTT client 1 is aware of the MCPTT IDs of the participants.
NOTE 1: Selection of MCPTT IDs of the participants can be manual or from the user profile configuration data or by any other means. This is left for the implementation.
Figure 10.19.3.1.1-1: Ad hoc group call setup
1. User at MCPTT client 1 would like to initiate an ad hoc group call. The MCPTT client 1 initiates the ad hoc group call by sending the ad hoc group call request containing the list of participants to the MCPTT server. Encryption supported information element shall be set to true since end-to-end encryption is supported. An SDP offer containing the MCPTT client media parameters is included. If there is a floor request to transmit, then the ad hoc group call request contains an indication of an implicit floor request. If the MCPTT user of MCPTT client 1 has selected a functional alias, then the ad hoc group call request contains that functional alias. If the ad hoc group call request contains an implicit floor request it may also include location information.
If the MCPTT user at MCPTT client 1 initiates an MCPTT emergency ad hoc group call or the MCPTT emergency state is already set for the MCPTT client 1 (due to a previously triggered MCPTT emergency alert):
i. the MCPTT ad hoc group call request shall contain an emergency indicator;
ii. if the MCPTT emergency state is not set already, MCPTT client 1 sets its MCPTT emergency state. The MCPTT emergency state of MCPTT client 1 is retained until explicitly cancelled by the user of MCPTT client 1.
2. The MCPTT server accepts the ad hoc group call request if the ad hoc group call is supported and authorized. Otherwise reject the ad hoc group call request and do not continue with the rest of the steps. If authorised, it validates whether the number of invited participants is within the configured limit before proceeding with the call setup.
If functional alias is present, the MCPTT server checks whether the provided functional alias allowed to be used and has been activated for the user.
If location information was included in the ad hoc group call request, the MCPTT server checks the privacy policy of the MCPTT user to decide if the location information of MCPTT client 1 can be provided to other users on the call (refer to Annex A.3 "Authorisation to provide location information to other MCPTT users on a call when talking").
If an emergency indicator is present in the received MCPTT ad hoc group call request, the MCPTT ad hoc group is considered to be in the in-progress emergency state until this ad hoc group call is terminated; and
If an imminent peril indicator is present in the received MCPTT ad hoc group call request, the MCPTT ad hoc group is considered to be in the in-progress imminent peril state until this ad hoc group call is terminated.
The MCPTT server considers the ad hoc group call participants as implicitly affiliated to the ad hoc group.
3. The MCPTT server shall send the ad hoc group call request return message to MCPTT client 1 containing the below:
i. The MCPTT ad hoc group ID generated by the MCPTT server; and
ii. Result of whether the ad hoc group call is authorized or not
If the ad hoc group call request is not authorized, MCPTT client 1 shall not proceed with the rest of the steps.
4a-4c. The MCPTT server sends the ad hoc group call requests towards the MCPTT clients of the invited users based on step 1. While sending the ad hoc group call requests, the MCPTT server shall remove the information elements that are not required to be conveyed to the target MCPTT clients (e.g. MCPTT ID list of the users who are required to acknowledge)
5a-5c. The receiving MCPTT clients are notified about the incoming ad hoc group call.
6a-6c. The receiving MCPTT clients accept the ad hoc group call requests and send ad hoc group call responses to the MCPTT server. The response may also contain a functional alias of the responding MCPTT user, which is verified (valid and activated for the user) by the MCPTT server.
7. The MCPTT server sends the ad hoc group call response to MCPTT client 1 through the signalling path to inform about successful call establishment.
NOTE 2: Steps 5 to step 7 can start to occur before all of step 4 is completed since the MCPTT server do not require to wait for the previous ad hoc group call request to complete before sending the ad hoc group request to another participant.
8. If the initiating MCPTT user requires the acknowledgement from the invited MCPTT users, and the required MCPTT users do not acknowledge the call setup within a configured time (the "acknowledged call setup timeout"), then the MCPTT server may proceed with or abandon the call and then notify the initiating MCPTT user that the acknowledgements did not include all required members according to ad hoc group call policy from the user profile configuration. The MCPTT server may notify the initiating MCPTT user of all MCPTT users who did not acknowledge the ad hoc group call request within the configured time. This notification may be sent to the initiating MCPTT user by the MCPTT server more than once during the call when MCPTT users join or leave the MCPTT ad hoc group call.
9. MCPTT client 1, MCPTT client 2, MCPTT client 3 and MCPTT client 4 establish media plane and floor control resources.
NOTE 2: Step 9 can occur any time following step 7 if the conditions to proceed with the call are met.
10.19.3.1.2 Release ad hoc group call
The procedure focuses on the case where the MCPTT server releases an ongoing MCPTT ad hoc group call for all the participants of that ad hoc group call, since at least one of the release conditions are met e.g., due to hang time expiry, last participant leaving, second last participant leaving, initiator leaving.
Figure 10.19.3.1.2-1 below illustrates the signalling control plane procedure for the MCPTT server initiating termination an ongoing ad hoc group call.
Figure 10.19.3.1.2-1: Release ad hoc group call
1. It is assumed that MCPTT users on MCPTT client 1, client 2 and client 3 are already part of the ongoing ad hoc group call.
2. MCPTT server would like to release the MCPTT ad hoc group call which is ongoing e.g., due to hang time expiry, last participant leaving, second last participant leaving, initiator leaving.
3. MCPTT server identifies the participants of the ongoing ad hoc group call and generates ad hoc group call release request to release ongoing session. The MCPTT server cancels the in-progress emergency state or in-progress imminent peril state of the ad hoc group if the ad hoc group call is an emergency or imminent peril call respectively.
4. MCPTT server sends ad hoc group call release request via SIP core towards each participant of the ongoing ad hoc group call.
5. MCPTT users are notified about the release of the ad hoc group call.
6. MCPTT client(s) receiving ad hoc group call release request, acknowledge towards the MCPTT server by sending an ad hoc group call release response.
NOTE: If the initiator of the ad hoc group call does not supply the participants list, the MCPTT client(s) may choose to store the list of participants for easy re-initiation of another ad hoc group call with the same participants.
7. MCPTT client 1, client 2 and client 3 have successfully released the floor control and media plane resources associated with the ad hoc group call that is terminated and the ad hoc group ceases to exist (i.e., further call is not possible over the same ad hoc group.
10.19.3.1.3 Ad hoc group call setup with MCPTT server determining the participants lists
Figure 10.19.3.1.3-1 below illustrates the ad hoc group call setup procedure initiated by the MCPTT user and MCPTT client 1 wherein the list of participants is determined by the MCPTT server based on the citeria received from the MCPTT client.
Pre-conditions:
1. The MCPTT user at MCPTT client 1 is authorized to initate ad hoc group call.
2. The MCPTT user at MCPTT client 1 wants to invite MCPTT users who are satisying certain criteria for the ad hoc group call.
Figure 10.19.3.1.3-1: Ad hoc group call participants determined by MCPTT server
1. User at MCPTT client 1 would like to initiate an ad hoc group call in-order to invite the participants satisfying specific criteria. The MCPTT client 1 initiates the ad hoc group call by sending the ad hoc group call request containing the details of the criteria to be applied by the MCPTT server for determining the participants list. If end-to-end encryption is supported, the Encryption supported information element shall be set to true and pre-configured MCPTT group whose configuration is to be applied is included. An SDP offer containing the MCPTT client media parameters is included. If there is a floor request to transmit, then the ad hoc group call request contains an indication of an implicit floor request. If the MCPTT user of MCPTT client 1 has selected a functional alias, then the ad hoc group call request contains that functional alias. If the ad hoc group call request contains an implicit floor request it may also include location information.
If the MCPTT user at MCPTT client 1 initiates an MCPTT emergency ad hoc group call or the MCPTT emergency state is already set for the MCPTT client 1 (due to a previously triggered MCPTT emergency alert):
i. the MCPTT ad hoc group call request shall contain an emergency indicator;
ii. if the MCPTT emergency state is not set already, MCPTT client 1 sets its MCPTT emergency state. The MCPTT emergency state of MCPTT client 1 is retained until explicitly cancelled by the user of MCPTT client 1.
2. The MCPTT server accepts the ad hoc group call request if the ad hoc group call is supported and authorized. Otherwise reject the ad hoc group call request and do not continue with the rest of the steps.
If functional alias is present, the MCPTT server checks whether the provided functional alias is allowed to be used and has been activated for the user.
If location information was included in the ad hoc group call request, the MCPTT server checks the privacy policy of the MCPTT user to decide if the location information of MCPTT client 1 can be provided to other users on the call (refer to Annex A.3 "Authorisation to provide location information to other MCPTT users on a call when talking").
If an emergency indicator is present in the received MCPTT ad hoc group call request, the MCPTT ad hoc group is considered to be in the in-progress emergency state until this ad hoc group call is terminated; and
If an imminent peril indicator is present in the received MCPTT ad hoc group call request, the MCPTT ad hoc group is considered to be in the in-progress imminent peril state until this ad hoc group call is terminated.
3. The MCPTT server shall send the ad hoc group call request return message to MCPTT client 1 containing the below:
i. The MCPTT ad hoc group ID generated by the MCPTT server; and
ii. Result of whether the ad hoc group call is authorized or not
If the ad hoc group call request is not authorized, MCPTT server and client 1 shall not proceed with the rest of the steps.
4. The MCPTT server determines the list of participants to be invited for the ad hoc group call based on the information present in the information element Criteria for determining the participants. This information element could carry either criteria or indicator identifying pre-defined criteria or a combination of both.
NOTE 1: The content of the Criteria information element, the details of the pre-defined criteria, and the way how their MCPTT server determines the list of participants are left to implementation.
5. The MCPTT server sends the ad hoc group call requests towards the MCPTT clients 2 and 3. While sending the ad hoc group call requests, the MCPTT server shall remove the information elements that are not required to be conveyed to the target MCPTT clients. This request carries the pre-configured group ID whose configuration is to be applied for this ad hoc group call if end-to-end encryption is requested. The MCPTT server considers the ad hoc group call participants as implicitly affiliated to the ad hoc group.
6. The receiving MCPTT clients are notified about the incoming ad hoc group call.
7. The receiving MCPTT clients accept the ad hoc group call requests and send ad hoc group call responses to the MCPTT server. The response may also contain a functional alias of the responding MCPTT user, which is verified (valid and activated for the user) by the MCPTT server.
8. The MCPTT server sends the ad hoc group call response to MCPTT client 1 through the signalling path to inform about successful call establishment.
9. The MCPTT server may notify the initiating MCPTT user of all MCPTT users who acknowledged the ad hoc group call request and joined the ad hoc group call. This notification may be sent to the initiating MCPTT user by the MCPTT server more than once during the call when MCPTT users join or leave the MCPTT ad hoc group call.
NOTE 2: The authorized user can learn who is currently affiliated to the current adhoc group call.
Editor’s note: How an authroized user determine the currently affiliated status of adhoc group is FFS.
10. MCPTT client 1, MCPTT client 2 and MCPTT client 3 establish media plane and floor control resources.
10.19.3.1.4 Modification of ad hoc group call participants by the initiator
Figure 10.19.3.1.4-1 below illustrates the modification of ad hoc group call participants procedure by the initiator of the ad hoc group call.
Pre-conditions:
1. The MCPTT client 1 is the initiator of the ad hoc group call.
2. The MCPTT users on MCPTT client 1, MCPTT client 3 to MCPTT client n are on an ongoing ad hoc group call.
3. The MCPTT user 1 requests to remove the user of MCPTT client 3 from the ad hoc group call and add user of MCPTT client 2 into the on-going ad hoc group call.
Figure 10.19.3.1.4-1: Modification of ad hoc group call participants by the initiator
1. The MCPTT client 1 sends the modify ad hoc group call participants request to the MCPTT server in order to remove MCPTT client 3 from the ongoing ad hoc group call and add MCPTT client 2 into it.
2. The MCPTT server verifies whether the MCPTT client 1 is authorized to add or remove (modify) the participants of the on-going ad hoc group call.
3. The MCPTT server sends modify ad hoc group call participants response to the MCPTT client 1.
4. The MCPTT server sends the ad hoc group call leave request to the MCPTT client 3 in order to remove it from the on-going ad hoc group call.
5. The MCPTT client 3 notifies the user of the ad hoc group call leave request.
6. The MCPTT client 3 sends the ad hoc group call leave response to the MCPTT server.
7. The MCPTT server removes the MCPTT client 3 from the ongoing ad hoc group call.
8. The MCPTT server sends the ad hoc group call request towards MCPTT client 2.
NOTE: Steps 8 to 10 can occur at any time following step 3.
9. The receiving MCPTT client 2 notifies the user about the incoming ad hoc group call.
10. The MCPTT client 2 accepts the ad hoc group call request and send ad hoc group call responses to the MCPTT server. The response may also contain a functional alias of the responding MCPTT user, which is verified (valid and activated for the user) by the MCPTT server.
11. The MCPTT server may notify the initiating MCPTT user of all the users who are added to the on-going ad hoc group call. This notification may be sent to the initiating MCPTT user by the MCPTT server more than once during the call when MCPTT users join or leave the ad hoc group call.
12. The MCPTT server may notify the participants about the change in the participants list of on-going ad hoc group call.
10.19.3.1.5 Modification of ad hoc group call participants by the MCPTT server
Figure 10.19.3.1.5-1 below illustrates the modification of ad hoc group call participants procedure by the MCPTT server.
Pre-conditions:
1. The MCPTT client 1 is the initiator of the ad hoc group call.
2. MCPTT server determined the participants for the ad hoc group call based on the criteria specified by the MCPTT client 1 while initiating the ad hoc group call.
3. MCPTT server continuously evaluates the criteria to monitor the list of users who meets or not meets the criteria for participating in the on-going ad hoc group call.
4. The MCPTT server detects that the MCPTT client 5 satisfies the criteria and MCPTT client 4 stops to meet the criteria specified by the MCPTT client 1.
Figure 10.19.3.1.5-1: Modification of ad hoc group call participants by the MCPTT server
1. The ad hoc group call is established and on-going with the participants MCPTT client 1, MCPTT client 2, MCPTT client 3 and MCPTT client 4. The participants list is determined by the MCPTT server based on the criteria specified by the MCPTT client 1 while initiating the call
2. The MCPTT server detects that the MCPTT client 5 satisfies the criteria specified by the MCPTT client.
3. The MCPTT server sends the ad hoc group call request to the MCPTT client 5.
4. The MCPTT client 5 notifies the user about the incoming ad hoc group call.
5. The MCPTT client 5 accepts the ad hoc group call request and sends the ad hoc group call response to the MCPTT server.
6. The on-going ad hoc group call is updated by adding MCPTT client 5 which satisfies the criteria specified by the MCPTT client 1.
7. The MCPTT server detects that the MCPTT client 4 is no more satisfying the criteria to be the participant of the ad hoc group call.
8. The MCPTT server sends the ad hoc group call leave request to the MCPTT client 4 and removes it from the on-going ad hoc group call.
9. The MCPTT client 4 notifies the user of the ad hoc group call leave request.
10. The MCPTT client 4 sends the ad hoc group call leave response to the MCPTT server.
11. The on-going ad hoc group call is updated by removing MCPTT client 4, which no more satisfies the criteria specified by the MCPTT client 1.
Annex A (normative):
MCPTT related configuration data