Figured I'd clear some of this up. I've been with NYCEMS and FDNY EMS (EMS Merged into Fire in 1996) for 27 years. I'm currently a Lieutenant. When I started the job, the practice was we would go to the Precinct and sign out an NYPD Portable, as portable radios were scarce in some stations. The NYCEMS portable ALWAYS had NYPD on them. When I started they had just completed the transition to Motorola MX300 radios. 8 to 10 channels with a zone A and B switch if I remember. We had all the NYCEMS freqs, plus NYPD according to the Borough you worked in. In 1986 for the Statue of Liberty Centennial/Operation Sail we received MX360 radios, with multiple zones. After that, no matter where you worked, you could come up on any Precinct freq.
After the MX360's were phased out, we got Sabre, and then Astro Sabre radios. Life was great until NYCEMS was merged into FDNY. Then for some reason FDNY decided we did not need NYPD on the radios. We got the NYPD freqs back in the mid to late 2000's after much debate about the failure of comm during 9/11. Ya think?
Now we have all NYPD freqs on the radios, including Citywide, and in some cases the Special Operations freq. The problem we have is during the time we did not have the freqs, we had a huge turnover of people both in EMS and NYPD. The result being that we know have a whole generation that needs to be schooled on the radio etiquette involved.
NYCEMS was actually dispatched over NYPD radio for many years, up to the early 1970's, so the relationship has always been there. It's a matter of public safety. Given the advent of 9/11, it's the smart thing to keep in play. Now if they just give me my old MX360 back, I'd be happy. They were old, but the ALWAYS worked. Be safe.
Ed