We’re replacing 110 aging UHF portables and moving to a P25 Phase II system that can patch to the sheriff’s dispatch during events on our 22‑acre campus. If you’ve executed a similar cutover, I want practical lessons — encryption key exchange with partner agencies, stairwell coverage testing, man‑down/indoor location — how did you stage it so custody posts never lost comms after 1800 or on weekends?
Run a 48-hour ‘patch burn-in’ before the cutover: keep each custody post’s legacy UHF live as a shadow while you console-patch the new P25 Phase II primary TG to the sheriff and walk your 22-acre campus for ‘stairwell coverage’ with radios on normal power. We didn’t turn on AES or man-down until that burn-in was clean — doing encryption first had OTAR/key sync hiccups that looked like dead spots and spooked posts.
Pre-stage OTAR with sheriff; 10-minute ‘stairwell coverage’ walk-test per wing on the 22‑acre campus. Man-down needed a sensitivity tweak.