The present document defines the Terrestrial Trunked Radio (TETRA) system supporting Voice plus Data (V+D). It specifies: • the interworking of individual calls between TETRA networks; • the supplementary services interaction with individual calls between TETRA networks. 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 sub-parts: • Transport layer independent General design [2]; • General Design, PSS1 over E.1 [3]; • General Design, SIP/IP [4]; • Transport layer independent Additional Network Feature – ISI Individual Call (ANF-ISIIC) (the present document); • Transport layer independent Additional Network Feature – ISI Group Call (ANF-ISIGC) [5]; • Transport layer independent Additional Network Feature – ISI Short Data service (ANF-ISISDS) [i.8]; • Transport layer independent Additional Network Feature – ISI Mobility Management (ANF-ISIMM) [6]; • Generic Speech Format Implementation [i.7]. The present document is the ANF-ISIIC sub-part. Like all other Additional Network Feature (ANF) specifications, those of ANF-ISIIC are produced in three stages, according to the method described in Recommendation ITU-T I.130 [i.4]. The present document contains the stage 1 and 2 descriptions of ANF-ISIIC, and 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. And the stage 3 description of ANF-ISIIC specifies its protocol.