You are asking a question that most of us have been scratching our heads over for a long time. The VHF frequencies for A-Deck are not encrypted but the patches to the digital system are, go figure. My only thinking as to why this would be done, that they don't want fireground traffic to be heard widespread throughout the valley like the K-Deck? Although with the VHF channels I can still pickup a few of them out here in Pinal County. I am just grateful that more of the system isn't encrypted.Phoenix Fire has Rescue units, which are staffed with FF/Paramedics. But cities like Chandler and Tempe, then, are staffed with civillian employees (according to what I read on Tempe's site, anyway).
By the way, to avoid writing an extra post, does anyone know the reasoning beyond Phoenix Dispatch's decision to encrypt the fire A Patches, but not Mesa to encrypt their B Patches? I mean, it would make life a ton easier as currently, I go to the bedroom (my BC340CRS), to listen to fires because its telescoping antenna seems to allow me to catch distant signals better than the rubber on the handheld.
All I'm saying is there's no rhyme or reason fo Phoenix to encrypt their A patches if Mesa isn't.