Wow, almost a year without the right answer?
27.635 seems to be where the European FT8 digital CB operators hang out. FT8 is mostly used on the amateur bands for quick weak signal contacts. The software to decode is WSJT-X. Usually you'll see a call sign, often made up and self assigned in CB, a grid square, which will tell you about where the station is located, and a signal report number between -24 & 24.
This doesn't seem to be as popular in the states as it isn't a normal FCC CB channel and US CB still seems to be voice only in practice. If freebanding is your thing, you might want to give this a try, it takes advantaged of short skip openings and can work with very weak signals. There isn't much to say other than call/grid/report but I've been enjoying it over on the 10 meter ham band while I work from home.