Here are their licenses
So far I'm unable to locate any 900 MHz info for them.
WNZL697
AMERICAN MEDICAL RESPONSE INC
Control Points
1 4 TECH CIRCLE, MIDDLESEX, NATICK, MA
P: (508)653-1140
Transmitter Address /Area of Operation
150 WABAN HILL RD
WABAN, MA MIDDLESEX County
159.570
4 TECH CIRCLE
NATICK, MA MIDDLESEX County
160.020
WPMD672
American Medical Response, Inc.
Transmitter Address /Area of Operation
NOBSCOT HILL
FRAMINGHAM, MA MIDDLESEX County
151.4675
WPMX533
American Medical Response, Inc.
Transmitter Address /Area of Operation
NOBSCOTT HILL
FRAMINGHAM, MA MIDDLESEX County
152.450
157.665
WPNU854
American Medical Response, Inc.
Transmitter Address /Area of Operation
8 SIDNEY ST
WAKEFIELD, MA MIDDLESEX County
151.0475
155.3550
159.1275
WPRV767
AMERICAN MEDICAL RESPONSE INC
Transmitter Address /Area of Operation
4 TECH CIRCLE
NATICK, MA MIDDLESEX County
153.215
158.415