4.7 Overview of MCPTT identifiers

22.1793GPPMission Critical Push to Talk (MCPTT)Release 17Stage 1TS

The main identifiable entities in use by the MCPTT Service are Mission Critical Organizations, MCPTT Groups, MCPTT Users, and MCPTT Administrators. The UEs are identified at the transport or network layer, but in some situations they might also be identified by the MCPTT Service. Each identifiable entity is distinct from all others and has an identifier (ID) associated to it, unique within a proximate identity domain. Those domains correspond to identifiable entities and can be nested within other domains in a multi-level hierarchical fashion. For example an MCPTT User might have an identifier unique within the domain corresponding to a Mission Critical Organization. The top-down concatenation of identifiers can generate unique identifiers within larger contexts, eventually leading to the identifiers being globally unique.

Each identifier can be associated with one or more aliases, which can be used for displaying and selection purposes. Some aliases are shortened equivalents of the identifier used for efficient signalling and are not intended for human interactions. At a minimum, each entity has one alias (default) which is the alphanumeric representation of its identifier. Most entities have a main alias, which is the entity’s name. Some aliases can be pictures, icons or other graphic representations. It is up to the implementation to decide if aliases have to be unique and if so, within which domain. Finally, some aliases are public, can be created/deleted only by authorized persons and are available to the MCPTT Service, while other aliases are private, can be created/deleted by their owners and might be residing only on certain UEs or be part of some private address books.

It is possible in principle for User IDs, Group IDs, as well as for aliases, to be defined system wide with certain values, but have different values for each application: e.g., the system wide User ID might be different from the MCPTT User ID and different from the video User ID for the same user. However, this type of separation might not be beneficial, and in practice only one identifier is likely to be used.

For simplicity, the term "User ID" is employed to identify an MCPTT User, without distinction of whether it is an identifier or an alias.