Something I forgot to mention about Smart Zone systems is that at least one mobile must be turned on and "talking" to a site before that site transmits anything. Just like cell phones, trunked radios and the site communicate via the control channel frequently, whether the mobile is transmitting voice or not. Sites are constantly searching for mobile units and are controlled according to the number of units in its coverage area and what talkgroup those units are set on.
So, if you are trying to receive the transmissions of a system in an area where you can only receive one site and there are not any mobiles turned on in the area served by that site, you will hear nothing. Getting back to the SCE system I listen to in the mountainous region I live in, there are sites which serve areas with very little population and without any fixed facility such as a hydro plant or office. If a mobile does not travel there during the time I'm in that area, I hear none of the system wide traffic being broadcast on other sites which have a mobile or fixed facility in the area it serves. I'm lucky in the town I'm in as there is a service center with an office, shop, and parking for service trucks about 1/2 mile from my home. There is at least one radio on all the time and it keeps the site I listen to transmitting voice all the time, even though there might not be anyone on duty in the area.
There is a flip site to this lack of ability to hear system wide traffic when you live in a remote area without a larger population, as portions of Utah have. You only hear traffic on the system if there are units active in the area you live in, so you don't have to hear the out of area of traffic. For example, you won't have to listen to game wardens running plates and drivers licenses along the Wasatch front if you live in Richfield, but should a warden or conservation officer (I'm not sure what they call them in Utah) have his/her radio on in the area served by a site you listen to in Richfield you are going to hear any traffic that officer hears. The Utah system (UCAN?) might be set up to transmit the traffic from the Wasatch front statewide, which is often the case with fish and game agencies who usually have one statewide dispatcher. For other agencies such as the highway patrol you may only hear local traffic or local District wide traffic when each district has a dispatcher. Then at night with less traffic several districts might have only one dispatcher and all of the district dispatch talkgroups might be patched together during that time. The beauty of wide area trunked systems, especially Smart Zone systems, is the flexibility given to the operators, and the ability for a mobile unit to travel all over the system and still be reached on one talkgroup, if the system is set up that way.
Given this flexibility I can only speak very generally about Smart Zone systems as the way one is designed and operated in another state or by other agencies can be very different.
The discussion in my previous post of the PRO-96's or a similar scanner's ability to switch from site to site is a moot point if you aren't mobile and only monitor one site.
If you are confused at this point by what I've written I would not be surprised. Trunking, especially involving systems with mulitiple sites, can be mysterious at first. Don't worry, a lot of listening will take most of the mystery away.
