Motorola MTP850 Ex Product Information Manual page 53

Group Call (TMO)
A Broadcast call will take precedence over any other call that has the same or lower call priority.
The terminal does not allow the user to transmit in a broadcast call.
Limitations
The terminal does not have the ability to initiate a broadcast call.
2.2 Air Interface Aspects
2.2.1 Group Call
The terminal is able to make and receive group calls to and from other TETRA terminals with half-
duplex speech capability. Group call uses TETRA group call signalling as described in [Ref 1] and
[Ref 10] using direct set-up for incoming and outgoing calls.
Group calls are normally owned and cleared down by the infrastructure. However, group ownership
is supported by the terminal - see section 2.2.3 "Call Ownership" on page 2-11.
2.2.2 Talking Party Identification
The Talking Party is displayed as specified in section 3.2.4 "Calling Party Identification Presentation"
on page 2-15.
2.2.3 Call Ownership
The terminal accepts call ownership of a group call. When the terminal is the call owner it will send
an appropriate TETRA signalling when the user ends the call.
2.2.4 Transmit Request Queueing
Whilst another user is talking during an ongoing group call and "PTT during received Group Call"
codeplug is enabled, a user may request to transmit by pressing and holding the PTT button. The
system will see this action and inform the user that the request has been queued.
While the terminal is in Emergency Mode the transmission request is not ignored and the queuing is
ignored.
If the user releases the PTT button, the terminal sends a message to the system withdrawing the
request.
2.2.5 Transmission during the Group Call
Whilst another user is talking during an ongoing group call and "PTT during received Group Call"
codeplug is disabled, a user cannot transmit by pressing and holding the PTT button.
The terminal ignores the request to transmit without any indication. The user has to release and
then press again the PTT button to re-initiate a transmission request.
While the terminal is in Emergency Mode the transmission request is not ignored.
2.2.6 Call Restoration in Group Call
If the terminal roams to a new cell during a group call, it will attempt to continue the call on the new
cell, using TETRA cell reselection and call restoration procedures.
If the terminal roams while the user is the transmitting party in the group call, and it is possible to
perform announced cell reselection, announced cell reselection will be employed as described in
section 10.4 "Roaming" on page 2-33 and call restoration procedures will be performed in the new
cell.
March 2009 Chapter 2 - MTP850 Ex/MTP810 Ex Product Information Manual
2-11
6866588D21-D