LPT: Memorize the military alphabet (Alpha, Bravo, Charlie, etc.). It will make giving letters and numbers over the phone so much easier.

E.G., you have a confirmation code of DRCWPL4509.

Old way:

"It's D as in Dog, R as in Rachel, C as in Carl, W as in Wolf, P as in Paul--"

"B as in Ball?"

"No, P as in Paul, like Paul Revere, P as in Pizza...L as in Laura, four five zero nine"

"So that's D as in Dog, R as in Rachel, K as in Karl--"

"No, C as in Carl, the other spelling, C like Cat"

"Ah, so it's D as in Dog, R as in Rachel, C as in Cat, W as in Wolf, P as in Paul, P as in Pizza--"

"Just one P"

"...P as in Paul, L as in Laura, four five zero nine?"

"I think so, yes"

New way:

"The code is Delta Romeo Charlie Whiskey Papa Lima four five zero nine"

"So that's DRCWPL4509?

"Right"

Full list of military alphabet here.

I taught myself this trick for this exact purpose (having never been in the military before), and it works every time. It works even if the call quality is poor, even if English is not their first language, even if the other person is a bit dim.

I mean, hey, if it's good enough for soldiers yelling codes over the radio while bombs are exploding a few dozen feet away, it's good enough for you and the worker bee on the other end of the call.