Private Call (TMO) 2-15
March 2009 Chapter 2 - MTP850 Ex/MTP810 Ex Product Information Manual 6866588D21-D
3.1.7 Terminating a Private Call
The user is given the ability to terminate a half-duplex or full-duplex private call by pressing the
<End/Cancel> key.
3.2 Air Interface Aspects
3.2.1 Half Duplex Private Call
The terminal is able to make and receive private calls to and from other TETRA terminals with half-
duplex speech capability. This call type will use TETRA individual call signalling.
All private calls are initiated using the ‘On-off hook’ method. For incoming calls, both direct and on-
off hook setup will be accepted by the terminal.
3.2.2 Full Duplex Private Call
The terminal is able to make and receive private calls to and from other TETRA terminals with full-
duplex speech capability. It is possible to provision the terminal to not allow the user to initiate Full
duplex private calls.
The terminal always initiates full duplex private calls using on/off hook signalling with the traffic
channel allocated by the SwMI only after the called party has answered the call. Therefore, all
progress tones during call setup will be generated by the terminal. In addition, the terminal will allow
the SwMI to modify the call setup to ’direct’, thereby enabling the infrastructure to generate the
progress tones.
3.2.3 Call Restoration in Private Call
If the terminal roams while the user is the transmitting party in the private 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
If the user is not the transmitting party, Unannounced cell reselection will be employed, followed by
call restoration procedures.
3.2.4 Calling Party Identification Presentation
The calling party TETRA identity may be transported as part of the incoming individual call set-up
signalling (as described in [Ref 1]). If the identity can be interpreted as a short number (see
Paragraph 13.1 "Short Addressing Schemes"), the short number is displayed to the user. In addition,
if the number is programmed in the terminal address book, the name associated with that number is
displayed as well.If the calling party identity is not present in the call set-up signalling, the terminal
displays a blank line in place of the missing identity.
3.2.5 Private Call Modification
If a Private Duplex call is initiated by the terminal, and the SwMI modifies the call to a Group call, or
a Half-Duplex Private call, the terminal will accept the modification and present it to the user. In
addition, if a half-duplex private call is initiated as a direct call, the terminal will accept modification to
an on-off hook call, and vice-versa.
If the SwMI modifies a call from hook to direct the terminal will accept the modification.
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