I did a quick search and found some potential answers for you...
452.6625 -- "Racing Radios Inc." has 159 different locations for this frequency, many in NH. There are other licensees on that frequency, including an 87 Watt (ERP) trunking system on Mount Uncanoonuc (registered to "Ed Cunningham," seemingly as a trunking provider... So various clients may be on it if that's what you're hearing.)
155.3400 -- a statewide (?) ambulance-to-hospital frequency. Each hospital in an area has its own PL code, and when they're in transit, they'll talk to the hospital about the patient they've got. Somewhere out there is a list of nearby hospitals on 155.34 and what PL tones they use.
155.3625 -- AMR (private ambulance provider) out of Pelham seems to be the only licensee in the state, with some locations in MA on the same.
463.9000 -- Beltronics, a common 'reseller' of repeaters... Towers on Uncanoonuc and in Hollis.
464.1500 -- looks like another Ed Cunningham frequency
As always, confirm through listening whether the listed licensee makes sense!
