9 Identities

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

9.1 Elementary identities for group calls

a) Group ID

The group ID is a sequence of decimal digits with a maximum length depending on the composition of the group call reference defined under c). The length of Group ID shall be in a range of 1 to 8 digits.

The mobile station derives the group ID from the group call reference by identifying the longest group ID amongst those stored in the SIM/USIM and matching the least significant digits of the group call reference. If no group ID is stored in the SIM that matches the least significant digits of the group call reference, the mobile station is not able to derive the group ID from the group call reference.

NOTE 1: The network should use Group IDs matching an initial part of other group IDs with greatest care, if at all.

EXAMPLE: A mobile station storing the group IDs 678, 2 678 and 42 678 (and only those) in the SIM will derive group ID 2 678 from group call reference 13 452 678.

For definition of Group ID on the radio interface, A interface and Abis interface, see 3GPP TS 44.068 [11].

For definition of Group ID coding on MAP protocol interfaces, see 3GPP TS 29.002 [13].

b) Group call area ID

The group call area ID is a sequence of decimal digits uniquely assigned to a group call area in one network and with a maximum length depending on the composition of the group call reference defined under c).

c) Group call reference

Each voice group call in one network is uniquely identified by its Group call reference. The group call reference is a concatenated sequence of the group ID (as the least significant part) and the group call area ID (as the most significant part). The group call reference shall have a maximum length of 8 decimal digits. The composition of the group call area ID and the group ID can be specific for each network operator.

Group call area ID

Group ID

The group call reference is equal to the group ID when the group ID has a length of 8 decimal digits.

For definition of Group Call Reference (with leading zeros inserted as necessary) on the radio interface, A interface and Abis interface, see 3GPP TS 24.008 [7], 3GPP TS 44.018[5] and 3GPP TS 44.068 [11].

For definition of Group Call Reference coding (also known as ASCI Call Reference, Voice Group Call Reference or Voice Broadcast Call Reference) on MAP protocol interfaces, see 3GPP TS 29.002 [13].

NOTE 2: If prefixes are used together with group IDs, the least significant digit of the group call area ID contains the prefix.

9.2 Use of identities in the network

For each voice group call the identifications as defined in the following shall be used within the network for the related purpose mentioned.

For voice group call services which are to operate in more than one PLMN, group identities have to be co-ordinated between the network operators involved.

a) Identities used for GCR requests for service subscriber originated voice group calls

For a service subscriber originated call, the identity of the call used by the MSC in which the call is originated to interrogate the GCR shall consist of the originating serving cell identity as defined in 3GPP TS 48.008 and the group ID as defined in subclause 9.1. In a RANflex configuration (with or without group call redundancy) the same identity is used by the group call serving MSC to interrogate the GCR when it receives the MAP Send Group Call Info service.

Originating cell ID

Group ID

A service subscriber initiating a voice group call has to call the wanted group ID. The MSC in which the call is originated shall accumulate from the BSS the called group ID and the originating cell ID.

If the group call area exceeds one MSC area, the identity used to interrogate the GCR by an MSC in which the call was not originated shall consist of the group call reference as defined in subclause 9.1, except for the case in a RANflex configuration (with or without group call redundancy) where the GCR interrogation in the group call serving MSC is triggered by receipt of the MAP Send Group Call Info service.

Without a RANflex configuration: If the group call area exceeds one MSC area and the call was originated

– in a relay MSC,

this relay MSC will perform a second GCR interrogation when the anchor MSC sets up the link to the relay MSC (see subclause 11.5).

In a RANflex configuration: If the group call area exceeds one MSC area and the call was originated

– in a relay MSC; or

– in a location area for which a relay MSC is the group call serving MSC,

this relay MSC will perform a second GCR interrogation when the anchor MSC sets up the link to the relay MSC (see subclause 11.5).

In a RANflex configuration with group call redundancy: If the group call area exceeds one MSC area and the call was originated

– in a relay MSC; or

– in a location area for which a relay MSC (belonging to a redundancy pool) is the group call serving MSC,

this relay MSC or another relay MSC belonging to the same redundancy pool will perform a second GCR interrogation when the anchor MSC sets up the link to the relay MSC (see subclause 11.5).

Independent of the configuration for the second GCR interrogation the relay MSC shall use the group call reference as defined in subclause 9.1 as the identity.

b) Identities used for GCR requests for dispatcher originated voice group calls

In case of dispatcher originated call the identity used by the MSC to interrogate the GCR shall consist of the group call reference as defined in subclause 9.1.

c) Identities used for notifications to service subscribers

Identities used for notification messages shall consist of the group call reference as defined in subclause 9.1.

d) Identities used by dispatchers for voice group call establishment

For dispatcher originated calls an MSISDN is dialled. 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 calls. The numbering scheme is based on ITU‑T Recommendation E.164. The Subscriber Number (SN) is used to indicate:

– the request of a group call by use of a prefix. The length of the prefix shall be 1 to 2 digits;

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

CC

NDC

Prefix

Group call reference

e) Identities used for VLR requests for service subscriber originated group calls

The group ID shall be used on the B-Interface for VLR requests.

f) Anchor MSC address for routing of service subscriber originated calls from originating MSC to anchor MSC

For service subscriber originated calls an anchor MSC address is used as called party address to route the call from the originating MSC to the anchor MSC. The anchor MSC address structure is the same as for dispatcher originated calls (see subclause d)) The Country Code (CC) and National Destination Code (NDC) are used as normal for routing purposes. The numbering scheme is based on ITU‑T Recommendation E.164. The Subscriber Number (SN) is used to indicate:

– the request of a group call by use of a prefix. The length of the prefix shall be 1 to 2 digits; the actual value of the prefix may be different than the one dialled by dispatchers.

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

CC

NDC

Prefix

Group call reference

g) Identities used for notifications to dispatchers

Identities used for notification messages to dispatchers shall be identical to those used by dispatchers to initiate calls as described in subclause d).

A notification identity is presented to a dispatcher terminal by making use of CLIP. Between the anchor MSC and MSC to which the dispatcher is attached, the information may be carried using the Calling Party Number parameter or Generic Number Parameter as agreed between the network operators. The Country Code (CC) and National Destination Code (NDC) are used as normal for routing purposes. The numbering scheme is based on ITU‑T Recommendation E.164. The Subscriber Number (SN) is used to indicate:

– the indication of a group call by use of a prefix. The length of the prefix shall be 1 to 2 digits; the actual value of the prefix shall be the same as the one dialled by dispatchers

– the group call reference as defined in subclause 9.1.

CC

NDC

Prefix

Group call reference

The Screening Indicator shall be set to “Network Provided”

The Type of Number shall be set to “International”