As most are aware, aside from a few who are grandfathered in, any callsign spelled out with letters is read out one letter at a time using the phoenetic code.
Please consider this if you are using a callsign for an airline whose callsign is included in the system-generated list.
For example, on Approach, it is agonizing to have Channex read out as Charlie Hotel Alpha November November Echo X-Ray every time, remembering that for every instruction sent which includes this long readout, there’s an ack in return from the pilot.
They may not be “offensive,” but they are a nuisance, especially when in a busy airspace such as the FNF hub and everyone has to continually hear this read out letter by letter delaying the audio each time by a not-insignificant amount of time.
(If you’re having trouble finding ones that aren’t in alphabetical order, like Lindbergh or Endeavor as Delta codeshares, please Google or look through the list. It’s most likely included, as the list is very inclusive.)