Been listening the the Fort Worth Oncor P25 site most of the day, trying to identify some talkgroups. First thing I noticed is the Unit IDs are basically the last four digits of the Radio ID for most users. They rarely give addresses or location data, mostly just something like "just north of where my truck is" so they must rely on AVL quite a bit. The one address I did get was in Keller. It associated with TG 143, they were talking freely, like on a talk channel. Seems like the Talkgroups must align with their service boundaries.