"Call Signs", also known as "Call Letters", are those alphabaic sets of letters issued by the FCC to identify licensed radio stations.
Unlicensed low power stations in the Part 15 service are neither issued call signs nor required to have any ID, but are free to call their stations by any name desired, except that it may not be confused with an existing licensed station. Many Part 15 stations elect to use spare letter sets, not currently assigned to a licensed station.
There are more spare letter sets than you might imagine.
REC Nets List of Spare Call Signs
ZOWIE!!!
How did you find this?
Brooce, Part15, Hartford CT
The site is maintained by Michelle Bradley, a fellow Part 15 Operator, Amateur Radio Operator and FCC Consultant. I agree with Carl, there is a treasure trove of good info on this site.