Hello,
220 to 222 has an interesting history in the Boston MA area. I remember when there were several ACSSB systems all over the area, then down to a couple that seemed to hold on for a long time. They are all gone now.
The AMTS (217) band had a Passport LTR system from 2004 and then it seemed like it was gone several years later. I remember Mobex had Passport LTR systems in NYC, Philly, and DC.
The major use of both 217 and 220 bands around the area is for Positive Train Control (PTC) for Railroads. These are mainly data transmissions. AMTRAK and MBTA commuter rail on 217 and freight railroads on 220.
73 Eric