How would it be any different than if the region switched to VHF or DMR or anything else. It’s the same as what it equipment and supplies are required to have: there are policies on what you have to have and if you don’t then you are out of service. And I can’t speak for every area, but you don’t need to worry about what other agencies are doing when there is a call. If you need to know, your dispatch tells you. When PD clears a scene for you, they either tell you directly or tell their dispatch to tell yours to tell you.