Back before the cellular network had internet capabilities like it does today (I'd say 1997 or so was when laptops started appearing at least in webster, south bridge and oxford police cars) The local departments used VHF or UHF conventional or repeaters for the laptops also known as MDTs.
As I recall South bridge used 155.9175 - If you look at the emissions designator 11K2F3D DTMF or other audible, non-frequency shift signaling, such as Whelen outdoor warning sirens. Back in the day you would just hear digital noise on the frequency. Before southbridge police had laptops during snow storm Car ticketing 158.850 was non stop for hours with license Plates. I would still keep the 155.9175 frequency in the scanner maybe you will catch some simplex comms.
Dudley, Webster and Quinsigamond Community College Police and multiple
Other local police departments statewide used 155.130 for their MDTs as I recall. Most of the 155.130 licenses expired as Cellular phone technology improved.
As I recall Cellular Digital Packet Data (CDPD) came along but coverage was spotty or not available in some areas. around 2004 CDPD was shut down in the area. Then cellular networks grew to what we know them as today.