How often have you been on one end of a telephone conversation that went like this?
A: "Okay, give me the MAC address." B: "Zero zero, zero two, six bee--" A: "Six what?" B: "Bee." A: "Bee?" B: "No, bee!" A: "Dee?" B: "Yeah. Six bee, four dee--" A: "Four bee?"
...and so on. Many letters and sounds are easily confused over telephone conversations or distorted by background noise. It is subsequently worthwhile to every IT professional to memorize the NATO phonetic alphabet to better communicate fragile sounds.
The phonetic alphabet is a mapping of individual letters and numbers to specially chosen words which are unlikely to be mistaken for one another (for instance, none of the words in the phonetic alphabet rhyme). By substituting the NATO alphabet telephony for independent letters and numbers, you can ensure other parties (who also grasp the idea of the phonetic alphabet) can reliably interpret your communication. And you can avoid sounding like a character on a Saturday morning children's show, repeating, "A as in apple, B as in ball..."
NATO Phonetic Alphabet