User's Guide

Your radio can also be customised to allow you to select a channel only talkgroup. If you select a
channel only talkgroup your radio cannot make or receive group calls: it can only make or
receive individual calls.
You can enable Presence Checking so that your radio checks whether the receiving radio is
available to receive when you attempt an Individual call. See DMO options on the facing page.
Using a DMO gateway
A DMO gateway (or gateway) is a device which allows users working in Direct Mode to
communicate with users in Trunked Mode effectively extending the working range of a radio. When
your radio is in DMO Mode and it is in range of a DMO gateway the gateway icon appears and,
if customised, an audible alert is generated. You can now make and receive group calls to TMO
radios (and to the dispatcher) via the gateway. See DMO gateway operationon page1.
If your radio is outside the range of a gateway, you may still be able to hear the speech of another
user who is in range of a gateway and who is involved in a group call via the gateway. In this case the
Communication Mismatch icon is displayed to indicate that you cannot take part fully in the
call. If you attempt to respond to the overheard speech, any radios within gateway range which can
hear you also display a Communication Mismatch icon to tell them that the speech is not being
routed via the gateway to TMO users.
Using a DMO repeater
You can extend DMO Mode range by using a DMO repeater (repeater). If your radio detects a
repeater the DMO Repeater icon is displayed and your radio can communicate with any other
radios in the selected DMO talkgroup which are also within the range of the repeater. See Repeater
Mode on the facing page.
If a radio is within range of a repeater but for some reason a call cannot be set up through it your
radio attempts to set up the call in DMO Mode and the Communication Mismatch icon is
displayed to all members of the talkgroup to indicate that there may be members of the talkgroup
who cannot take part in the call.
80 SC21 Series hand-portable radio