scope:

The present document defines the Terrestrial Trunked Radio system (TETRA) supporting Voice plus Data (V+D). It specifies:

- general design aspects (e.g. reference points, numbering and addressing, or protocol architecture);

- the system bearer and mobility management services, and the corresponding air interface protocols;

- the interworking between TETRA networks;

- the interworking of TETRA networks with other networks, via gateways;

- the peripheral equipment interface on the mobile station;

- the security protocols and mechanisms applicable to TETRA networks and to TETRA terminal equipment;

- the supplementary services applicable to the basic TETRA tele- or bearer services.

The TETRA V+D interworking - basic operation part defines the interworking between TETRA networks over the corresponding interface: the Inter-System Interface (ISI). It comprises the following subparts:

- ISI general design;

- Additional Network Feature - ISI Individual Call (ANF-ISIIC); 

- Additional Network Feature - ISI Group Call (ANF-ISIGC);

- Additional Network Feature - ISI Short Data service (ANF-ISISDS);

- Additional Network Feature - ISI Mobility Management (ANF-ISIMM);

- 8 kbit/s encoding of user information at the ISI.

The present document specifies the Additional Network Function (ANF) - Inter-System Interface (ISI) Short Data service (ANF-ISISDS) which is part of the Interworking Basic Operation of the Terrestrial Trunked Radio system (TETRA) supporting Voice and Data (V+D). Specifically the present document details the stage 1, 2 and 3 aspects of the ANF-ISISDS as seen from the TETRA Switching and Maintenance Infrastructure (SwMI) point of view at the Inter System Interface (ISI). This service comprises of:

- TETRA user defined short message transmission over the ISI to individual and group addresses;

- TETRA pre-defined short message transmission over the ISI to individual and group addresses.

ANF-ISISDS enables short data and status messages to be set-up and transferred between a user registered in one TETRA network to another user registered in another TETRA network, operating at the ISI of both SwMIs.

Like all other Additional Network Feature (ANF) specifications, those of ANF-ISISDS are produced in three stages, according to the method described in ITU-T Recommendation I.130 [4]. The present document contains the stage 1 and 2 descriptions of ANF-ISIIC, and its partial stage 3 description. The stage 1 description specifies the ANF as seen by its users, which are essentially the individual call control entities in both TETRA networks. The stage 2 description identifies the functional entities involved in the ANF and the information flows between them. The partial stage 3 description of ANF-ISISDS specifies its protocol.