4 Descriptions
23.1353GPPMulticall supplementary serviceRelease 17Stage 2TS
4.1 Handling of Multicall
4.1.1 Provision
No special signalling procedures apply.
4.1.2 Withdrawal
No special signalling procedures apply.
4.1.3 Registration
The information flow for registration is shown in figure 1. The registration process is shown in figure 2.
Figure 1: Registration of Multicall
Figure 2: Process Register_Multicall_HLR
4.1.4 Erasure
No special signalling procedures apply.
4.1.5 Activation
The service provider shall provide an initial value for Nbr_User when activating the service. No special signalling procedures apply.
4.1.6 Deactivation
No special signalling procedures apply.
4.1.7 Interrogation
The information flow for interrogation is shown in figure 3. The interrogation process is shown in figure 4.
Figure 3: Interrogation of Multicall
Figure 4: Process Interrogate_Multicall_VLR
4.2 Call related procedures
The procedures for basic call handling are specified in 3GPP TS 23.018. These shall also be used for Multicall.
4.2.1 MO call
Figure 5 shows the flow of information between network elements for an MO call:
Figure 5: Information flow for mobile originating call
4.2.2 MT call
Figure 6 and Figure 7 show the flow of information between network elements for an MT call:
– Case 1: When the MS requests a new bearer in call confirmed. (Figure 6).
– Case 2: When the MS requests a new bearer in Connect. (Figure 7).
Figure 6: Information flow for mobile terminating call (Case1)
Figure 7: Information flow for mobile terminating call (Case2)
4.3 Messages and their contents
This clause contains the detailed description of the information flows used by Multicall.
Each Information Element, IE, is marked as (M) Mandatory, (C) Conditional or (O) Optional. A mandatory information element shall always be present. A conditional information shall be present if certain conditions are fulfilled; if those conditions are not fulfilled it shall be absent. An optional information element may be present or absent, at the discretion of the application at the sending entity. This categorisation is a functional classification, i.e., stage 2 information and not a stage 3 classification to be used for the protocol.
The stage 2 and stage 3 message and information element names are not necessarily identical.
4.3.1 Messages between MS and MSC
Table 1 indicates messages between the MS and the MSC for mobile originating calls and mobile terminating calls. (Refer to TS 24.008).
The MS shall indicate the maximum number of bearers supported by the MS in the CC capabilities IE. The MS shall also indicate the maximum number of simultaneous speech bearers supported by the MS for future compatibility. For Release 99, the maximum number of simultaneous speech bearers is 1. If the MS does not indicate the maximum number of bearers the network shall assume it does not support Multicall.
The network supporting Multicall shall indicate the capability in the NW CC capabilities IE. If the NW CC capabilities IE is not sent from the network, the MS supporting Multicall shall assume that the network doesn’t support Multicall. If an MS initiating an emergency call is located in a network that does not support Multicall, the MS shall release one or more existing call to ensure that the emergency call can be established.
Table 1: Messages between MS and MSC
|
Message |
Message sender |
Information element name |
Information element Required |
Information element description |
|
Setup (MO) |
MS |
Stream Identifier |
M |
This information element indicates which bearer (new or existing) shall be used for the call. |
|
CC Capabilities |
C |
For the first call, this information element shall be included to indicate the maximum number of bearers supported by the MS. |
||
|
Emergency Setup |
MS |
Stream Identifier |
M |
This information element indicates which bearer (new or existing) shall be used for the call. |
|
Call Confirmed |
MS |
Stream Identifier |
M |
This information element indicates whether a new bearer is requested, i.e. SI=value which is not used by any of the existing bearers , or no bearer is requested at that point in time, i.e. SI="no bearer". |
|
CC Capabilities |
C |
For the first call, this information element shall be included to indicate the maximum number of bearers supported by the MS. |
||
|
Connect (MT) |
MS |
Stream Identifier |
C |
This IE shall be present in the Connect message if the SI contained "No bearer" in the Call Confirmed message, otherwise shall be absent. |
|
Setup (MT) |
NW |
NW CC Capabilities |
C |
This information element shall be present for the first call. |
|
Call Proceeding |
NW |
NW CC Capabilities |
C |
4.3.2 Messages on B interface (MSC-VLR)
4.3.2.1 Send Info For Outgoing Call
This message is specified in 3GPP TS 23.018. The following additional information element is required:
|
Information element name |
Required |
Description |
|
Total number of bearers in use |
M |
Total number includes the new bearer if requested for the call. |
4.3.2.2 Send Info For Outgoing Call negative response
This message is specified in 3GPP TS 23.018. The following additional information element is required:
|
Information element name |
Required |
Description |
|
Negative response information element |
M |
If the VLR detects that the OG call can not be permitted because Multicall limit set by the user is exceeded, it shall indicate " Nbr_User is exceeded" as the negative response information element value. If the VLR detects that the OG call can not be permitted because the user is not provisioned with Multicall, it shall indicate "Multicall not provisioned" as the negative response information element value. |
4.3.2.3 Send Info For Incoming Call
This message is specified in TS 23.018.
4.3.2.4 Send Info For Incoming Call ack
This message is specified in TS 23.018.
4.3.2.5 Send Info For Incoming Call negative response
This message is specified in TS 23.018.
4.3.2.6 Complete Call
This message is specified in TS 23.018.
4.3.2.7 Complete Call ack
This message is specified in TS 23.018.
4.3.2.8 Page MS
This message is specified in 3GPP TS 23.018. The following additional information element is required:
|
Information element name |
Required |
Description |
|
Nbr_User |
M |
Shall be present if the subscriber is provisioned with Multicall. |
4.3.2.9 Page MS negative response
This message is specified in 3GPP TS 23.018. The following additional information element is required:
|
Information element name |
Required |
Description |
|
Basic service list |
C |
If the MSC detects subscriber busy (More Calls Possible), the Basic service list shall be included, see Table 2. |
Table 2: Basic Service List setting
|
Condition |
Setting |
|
|
The terminating call type is speech |
There exists an active or held speech call |
Basic service of active call via the same bearer as the existing speech call. If an active call does not exist via the same bearer as the existing speech call "speech" shall be indicated. |
|
There exists no speech call |
All basic services of ongoing calls |
|
|
The terminating call type is not speech |
All basic services of ongoing calls |
|
4.3.2.10 Process Access Request
This message is specified in TS 23.018.
4.3.2.11 Process Access Request ack
This message is specified in TS 23.018.
4.3.2.12 Process Access Request negative response
This message is specified in TS 23.018.
4.3.2.13 Search For MS
This message is specified in 3GPP TS 23.018. The following additional information element is required:
|
Information element name |
Required |
Description |
|
Nbr_User |
M |
Shall be present if the subscriber is provisioned with Multicall. |
4.3.2.14 Search For MS ack
This message is specified in 3GPP TS 23.018.
4.3.2.15 Search For MS negative response
This message is specified in 3GPP TS 23.018. The following additional information element is required:
|
Information element name |
Required |
Description |
|
Basic service list |
C |
If the MSC detects subscriber busy (More Calls Possible), the Basic service list shall be included, see Table 2. |