Another Callsign Question

captainsimon wrote:

When flying the B738 in the dreamliner C/S I set the call sign to BOEING and the flight number to 6696 but the ATC does not say BOEING they just say 6696.

If I sat the callsign to any of the others like SOAR, GHIA or PACIFICA the ATC voice will say these call signs.

Is this a setting issue or a glitch?

I would think that BOEING wouldn't be recognized as a callsign because it's not an Airline but an Aircraft manufacturer.

SOAR, GHIA and PACIFICA are all airlines.