The TETRA individual call is a one-to-one call. It acts as ‘telephone’ call between two TETRA mobile radio’s. The calling party selects the ISSI or alias in the mobile radio telephone book or by typing in the number using the keypad. On the receiving party the call can be answered and the user is usually notified by ring indication.
Once the call is established a full duplex or half duplex call between the two radio’s can be made. When in TMO mode the network needs to support individual call and the user usually needs to have permission to make individual calls. The two users can be anywere in the network. In DMO mode only half duplex indivual call can be made.