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GENERAL OPERATION
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When a SMARTNET or SmartZone channel is 
selected or the radio is powered up on one of those 
channels, it searches for a control channel. Once a 
control channel is found, the alias (name) of the 
selected channel is displayed and the radio attempts to 
register on the radio system. If a control channel could 
not be found (because of an out of range condition or 
the system ID is not correct, for example), “NO SYS” 
(early units) or “Out Rnge” (later units) is displayed 
and the radio continues to search for a control channel.
The control channel transmits and receives 
system information to and from all radios registered on 
the system. Therefore, once a control channel is found, 
it is continuously monitored for incoming call infor-
mation and is used to make call requests. The radio 
automatically changes to a traffic channel to place and 
receive calls and then returns to the control channel 
when the call is complete. Operating features unique 
to SMARTNET/SmartZone channels are described in 
Section 6.
3.9.4  P25 TRUNKED MODE
The P25 Trunked operating features are very 
similar to the SmartZone type just described. Since 
SmartZone features are also similar to SMARTNET 
features, all three modes are described in the 
Section 6. Some differences between the P25 Trunking 
and SmartZone modes are as follows:
Digital signaling is always used with P25 calls. 
Either analog or digital signaling may be used for 
SmartZone calls.
Calls made to a specific radio in the P25 mode are 
called Unit Calls. In the SMARTNET/SmartZone 
mode they are called Private Calls. 
Messaging is not available with P25 calls.
The P25 control channel data rate is 9600 baud and 
the digital voice data rate is also 9600 baud. With 
SmartZone operation, the control channel data rate 
is 3600 baud (both digital and analog calls) and the 
narrowband digital voice data rate is 9600 baud.
The P25 mode uses a system ID, Wide Area 
Communications Network (WACN) ID, and RF 
Subsystem ID (RFSS). The SmartZone mode does 
not use the WACN and RFSS IDs.
P25 Unit IDs can be 1-16,777,215 (000001-FFFFFF 
hex) and SmartZone Unit IDs can be 1-65,535 
(0001-FFFF hex).
3.9.5  SYSTEMS, CHANNELS, AND ZONES
A zone and channel are selected to place and 
receive calls. The following describes the relationship 
between systems, channels, and zones.
Systems
A system is a collection of channels or talk 
groups belonging to the same repeater site. It defines 
all the parameters and protocol information required to 
access a site. Up to 16 systems of any type can be 
programmed. 
The maximum number of channels assignable to 
a system is limited to 512. Channels may also be 
limited by available memory space as described in the 
following information.
Channels
A channel selects a radio (RF) channel or talk 
group as follows:
Conventional Analog Mode - A channel selects a 
specific radio channel, Call Guard (CTCSS/DCS) 
squelch coding, and other parameters unique to that 
channel.
Conventional Project 25 Mode - A channel selects a 
specific radio channel, NAC squelch coding, talk 
group ID, and other parameters unique to that channel.
SMARTNET/SmartZone and Trunked Project 25 
Modes -
 A channel selects a specific talk group, 
announcement group, emergency group, and other 
parameters unique to that talk group.
A maximum of up to 512 channels can be 
programmed with the preceding modes. These chan-
nels can belong to a single system or multiple systems.