Section: 7.1 Group Identities
Content: Logical groups of subscribers to the Voice Group Call Service or to the Voice Broadcast Service are identified by a Group Identity (Group ID). Group IDs for VGCS are unique within a PLMN. Likewise, Group IDs for VBS are unique within a PLMN. However, no uniqueness is required between the sets of Group IDs. These sets may be intersecting or even identical, at the option of the network operator. The Group ID is a number with a maximum value depending on the composition of the voice group call reference or voice broadcast call reference defined in clause 7.3. For definition of Group ID on the radio interface, A interface and Abis interface, see 3GPP TS 44.068[ Group Call Control (GCC) protocol ]  [46] and 3GPP TS 44.069[ Broadcast Call Control (BCC) protocol ]  [47]. For definition of Group ID coding on MAP protocol interfaces, see 3GPP TS 29.002[ Mobile Application Part (MAP) specification ]  [31]. VGCS or VBS shall also be provided for roaming. If this applies, certain Group IDs shall be defined as supra-PLMN Group IDs which have to be co-ordinated between the network operators and which shall be known in the networks and in the SIM. The format of the Group ID is identical for VBS and VGCS.