I wish NATO phonetic was more commonly understood.

The brilliance is that it works in other languages too. Don't know about French/Italian but for a Norwegian it's usable. Only Charlie, Mike, and Yankee i think would not be understood if said as spelled in Norwegian.

The number of times I've started rattling off a string phonetically and just received confused silence in return.

With how good phone connections have generally gotten I usually just spell it out normally then specify phonetically on the sound-a-like letters in the middle where enunciation and/or attention span may affect reception "Context that's C-O-N as in Nancy-T-E-X-T"

Also providing the word before spelling it helps immensely because the recipient will already have an idea of what to expect and can verify afterwords that they transcribed correctly