Looking at the SNE list, I'd imagine many are gone, or reorganized into something else. Or they don't use two-way radios. Action Ambulance out of MA has several towns in Ossipee Valley area, which I believe was MedStar. They use a PTT-over-Cellular (PoC) system. Great Brook may have a two-way channel for portable to portable use, but they dispatch entirely on a PoC service as well. Brewster was up in Conway, although I'm not sure of they're still there, and they may be North Conway Ambulance. There are also several Ambulance Services that while they are lumped in with their municipal Fire Department, they are legally a separate agency. Those are almost impossible to know.
Then you have Stewarts, which is now a massive provider, a subsidiary of a larger company; and yet other than the occasional traffic up around Meredith, I've never heard a peep from them on dozens of searches I've done around Concord.
It probably requires a lot of searching by folks in the areas where these ambulance operate, maybe shaking a tree or two looking for whether the company uses PoC or two-Way RF, or "Who" dispatchers on the various fire dispatch channels call area EMS agencies, etc.
