User's Guide

Once the call is established, the characteristics of the new call are the same as those of any call of
that type. For example, if the new call is half-duplex, you need to press PTT before starting to speak,
releasing the PTT allows other parties to take the speech item, and the top microphone and half-
duplex loudspeakers are used.
When a radio is worn attached to your body, a half-duplex to full-duplex call modification can be
difficult to handle (since the latter is a telephone-type call). To overcome this, your radio can treat the
full-duplex calls (resulting from a half-duplex call modification) as if they are half-duplex calls, i.e.
using PTT before speaking and releasing it to hear the other party. (Making individual phone
calls (full-duplex mode) on page60.)
Changing the behaviour of the PTTduring TMO group calls
Your radio may be customised to allow you to talk back on your TMO selected group even if you are
currently receiving a group call from another talkgroup being scanned by your radio.
When enabled, pressing the PTT when in a received group call will start a new call on the radio's
selected talkgroup, allowing you to participate in that call whilst monitoring your current scanlist
activity.
There are two options:
To selected group—when the PTT is pressed in a received group call to a scanned group
(not the selected talkgroup), the radio leaves the existing call and starts a new call to the
scanned talkgroup.
To received group—when the PTT is pressed during a received group call, the radio
transmits in the current call.
If the PTT behaviour to set to the ‘to selected group’ option, and the radio is in a group call from a
scanned talkgroup that is not the currently selected talkgroup, an icon appears in the Call
Information Box. When the radio leaves the scanned group, to start a call to the selected talkgroup,
the icon is not displayed.
The behaviour of the PTT button can be set for all group calls using the PTT Behaviour option
available from the Options menu. Alternatively, you can override the default setting during a group
call by pressing the PTT context key (which toggles the two options) and select the PTT behaviour
that allows you to respond to the call. Your radio provides a notification message to show the change
of PTT behaviour (either ‘to selected group’ or ‘to received group’). When the call is terminated,
the behaviour of the PTT button reverts to that selected using the menu option.
If your radio is operating in Gateway mode, the radio can only respond to group calls in the selected
talkgroup (to selected group).
To set the PTT behaviour using the menu:
1. Select Menu > Options > Settings > PTT Behaviour.
2. Select the PTT behaviour (To received group or To selected group), then press the
Select context key.
64 SC21 Series hand-portable radio