Checking out some remote SDR receivers for activity on 11 meters elsewhere in the USA. Currently listening to 27.255 MHz CB channel 23 on a remote SDR in Ohio and am noticing a data link or possibly pager transmitter right on frequency. It will transmit an unmodulated carrier for about 1 second, followed by two data bursts about 0.5 seconds apart while "idling" - and when its busy its a series of data bursts. Reminds me of POCSAG. I know this frequency is one of the six available in the 26-27 MHz band under FCC rules Part 95 for data transmission. While the other five frequencies have a maximum carrier power of 4 watts, 27.255 MHz has a maximum carrier power of 25 watts, which means you can do a lot more with it as far as on-site paging systems go.
As my other logs will show, there is heavy use of the 11 meter band for paging systems, on-site pagers for hospitals, etc and for data link systems. I know if one data link system that is sold that uses 27.255 MHz and FSK modulation. I'm hearing bits and pieces of a CB QSO in AM mode underneath the data bursts but it is by far the primary user of this frequency even though band is open and basically every channel is in use.