This is just an idea - not supported by any experimentation, since I've never had a problem having the nice computer lady understand my AAdvantage number, but most computerized speech recognition programs are built to understand the phonetic alphabet.

If you don't know the phonetic alphabet, it can come in handy...

A - Alpha
B - Bravo
C - Charlie
D - Delta
E - Echo
F - Foxtrot
G - Golf
H - Hotel
I - India
J - Juliet
K - Kilo
L - Lima
M - Mike
N - November
O - Oscar
P - Papa
Q - Quebec (I was taught this is pronounced "Kay-beck")
R - Romeo
S - Sierra
T - Tango
U - Uniform
V - Victor
W - Whiskey
X - X-ray
Y - Yankee
Z - Zulu