They were on the Bearcom/Comtronics 900MHZ Con+ trunk, but disappeared a couple of months ago. They probably went to a LTE type system which can't be monitored. Brewster went to one a couple of years ago and Coastal/Fallon did just before MGH/Brigham disappeared.
Some other smaller companies in central Mass. have also disappeared from their VHF or UHF systems so they have probably done the same.