Supplementary Services 2-49
September 2008
Chapter 2 - MTM800 Product Information Manual 6866537D87-F
The lifetime of the Super Group is received by the terminal as part of the assignment signalling. If a
subsequent assignment to the same group is not received within that lifetime, the terminal will cease
monitoring that super group.
The terminal will also support Super Groups of scanned groups, such that a group addressed DGNA
assignment, received on one of the scan group addresses, will cause the terminal to monitor all
signalling addressed to that super group as long as the scan group is being scanned and as long as
the Super Group lifetime lasts.
14.1.6 DGNA Limitations
The following DGNA functionality will not be supported
• Call-related DGNA will not be supported.
• The terminal will not support functionality of the “authorized user”
• The terminal will not perform any network authentication before accepting DGNA.
14.2 Ambience Listening (AL)
This provides an authorized user (a dispatcher etc.) with the ability to cause a terminal to transmit
without giving any indication to the user and monitor the audio activity picked up by the terminal’s
hot microphone. In scenarios where Ambience Listening is activated, a higher mic gain can be
automatically selected to increase pick-up of “ambient” conversation.
AL is a special Individual Call to a user‘s terminal.
14.2.1 Call Maintenance
The terminal does not restrict the duration of the call.
14.2.2 User Actions
If the user requests a call set up, the AL (Ambience Listening) call is immediately dropped and the
user’s call will be initiated.
The terminal allows the user to perform other interface functionality that and will not release the call,
including access to most menu items, changing modes, changing talkgroups and the activation/de-
activation of scan lists. During talkgroup change, the terminal will appear to be performing the
attachment, but the signalling will only happen after the Ambience Listening call has been
terminated and no indication will be given to the user, unless attachment fails.
14.2.3 Pseudo Power Down
If the user powers down the terminal, all indications will be extinguished and the terminal will appear
to have powered down. In reality the terminal is still active in transmit mode for the Ambience
listening call and the will only shut down on call completion.
If the user again powers up the terminal from its pseudo powered down state, it will go through all
the power up indications as though powering up.
14.2.4 Call Termination
The AL call is disconnected when the Emergency Button is pressed, Transmit Inhibit engaged, or
DMO entered. Also the initiator can close the AL call.
Benefits:
❏ User Safety especially in Lone Worker scenario or at scene of incident to keep dispatcher
operator informed
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