Nice sentiment. Won't work in most places.

For example, our Firehouse. The phone number is 610-982-5710. Go ahead, call it. I'll wait. Unless you happend to call when there was someone there - which isn't very often - you'll get voicemail. It's a volunteer company - as are all of the surrounding companies. Unstaffed, response is via pagers & siren triggered by - you guessed it - the 911 center. While a 911 outage would not prevent them from tripping the pagers/siren, the steps that lead up to that dispatch would be missing. In fact, even big, paid fire companies leave the firehouse empty when on a call.

EMS, a paid service, is dispatched in the same way, and while they are staffed, if they are enroute back to station from a hospital trip, they are dispatched by radio...from the 911 center. Again, empty building, nobody there to answer the phone if they are on a call.

Police are a little different - they do have staff on duty 24/7 but they are not really equipped to self-dispatch.

My point: Don't think that having the phone number will matter.