Have a look through this page, specifically the
Affiliation section.
https://wiki.radioreference.com/index.php/Trunking_Basics
I did read that page, twice. I also considered that certain units were on-duty in a sector for a shift, and then once off-duty and there was no other unit in the area the rest of the day. However, that seems not to be the case.
I will go back to my example of Wright County (TG 64801), most days, during first shift, I can hear them on the Mason City tower (site 65). However, they quite abruptly disappear at about 1400, and never show up til after 0800 according to my logs. Again I say most days. True, it might be Affiliation, but not that regular, or over that geographic distance from their normal jurisdictions. Wright County is about 30 to 60 miles away from Mason City. Not all radios have that kind of range on 700 mhz, even if a mobile unit (versus handheld).
Same goes for ISP. While most of the traffic in a large geographic area around here has been using 2C (TG 5202), there are some using 5C (TG 5205) who are a very far distance away from the Mason City tower (one such case was a car in Decorah). Traffic on 5C has also been a regular occurrence on the Mason City tower, but only on the day shift.
At this point, let me set a few basic assumptions. First, using OP25 allows me to see, as they are talking, who is talking. For example, if ISP 150 is transmitting, it shows 11150 on the screen. If the dispatching desk for that District (Cedar Falls) is talking, I see 10978. Also on that line, it shows the current talk group, the frequency, and what slot on that frequency that is being used (slot 1 or slot 0). All that data is being translated from the Control Channel I assume.
All this is why I question if a particular dispatching center or desk, has the option to call up more than one tower at a time from his or her console (as could be done on the old Avtech) in addition to any Affiliation by cars which goes on.
