Codan Radio P25 Training Guide - Manual (Page 86)

TRAINING GUIDE | P25 RADIO SYSTEMS
Chapter 6: P25 Trunking Page 78
(1) Control Channel Hunt – the subscriber unit will hunt for the control channel by scanning its list
of pre-programmed channels for the OSPs that are continually broadcast from the trunking
controller.
(2) Registration Request – the subscriber will register with the trunking controller (RFSS). The
trunking controller can restrict access to only valid subscriber units and can record where that
subscriber is located within the network. Full registration or Location Registration can occur here.
(3) Registration Grant / Talk Group Affi liation – the trunking controller will grant access to the
subscriber and will assign a Working Unit ID (WUID) and Working Group ID (WGID) to the
subscriber.
(4) Idle – the subscriber will monitor the control channel until the subscriber requests a traffi c channel
or is assigned a traffi c channel based on another subscriber in the talk group requesting a traffi c
channel for that group.
(5) Traffi c Channel Request – the subscriber requests a traffi c channel for voice or data
communications.
(6) Traffi c Channel Grant – the trunking controller grants a traffi c channel to the subscriber and
notifi es the recipients of the voice or data message with a traffi c channel grant (typically a talk
group).
(7) Voice or Data Communications – All subscribers in the Talk Group access the traffi c channel and
communicate voice or data message.
(8) Call Termination – All subscribers in the talk group return to Idle (4) and monitor the control
channel.
TRAFFIC CHANNEL OWNERSHIP
The traffi c channel can be assigned to a talk group in two different ways.
Transmission Trunking assigns the traffi c channel for the duration of that transmission. Once the
transmission is over, the call is terminated. A new traffi c channel is assigned for the next transmission.
A conversation with multiple transmissions will require a new traffi c channel for each transmission.
Message Trunking assigns the traffi c channel to a talk group for the entire conversation. The conversation
is deemed to be fi nished when the delay between transmissions exceeds a preset time. The trunking
controller may terminate a conversation if the traffi c channel is required for a higher priority use.