There are callsigns for letters used in the English alphabet used by pilots and ATC personnel worldwide, as letters by themselves can sound alike, such as D and T for example, especially if radio reception is less than ideal. I only know a few like,

A=Alpha
B=Bravo
C=Charlie
D=Delta(The Greek alphabet for D, not the US airline)
E=Echo
F=Foxtrot(?)

I'd really appreciate if anyone here can come up with a full list of the alphbet callsigns, or direct me to any websites that lists such a thing!