A = 1 N = 14
B = 2 O = 15
C = 3 P = 16
D = 4 Q = 17
E = 5 R = 18
F = 6 S = 19
G = 7 T = 20
H = 8 U = 21
I = 9 V = 22
J = 10 W = 23
K = 11 X = 24
L = 12 Y = 25
M = 13 Z = 26
The NATO alphabet became effective in 1956 and, a few years later, turned into the established universal phonetic alphabet for all military, civilian and amateur radio communications. It assigns a word to each letter so that a letter's name begins with the letter itself.
For more information, see https://www.nato.int/cps/en/natohq/news_150391.htm
A = Alpha N = November
B = Bravo O = Oscar
C = Charlie P = Papa
D = Delta Q = Quebec
E = Echo R = Romeo
F = Foxtrot S = Sierra
G = Golf T = Tango
H = Hotel U = Uniform
I = India V = Victor
J = Juliet W = Whiskey
K = Kilo X = X-Ray
L = Lima Y = Yankee
M = Mike Z = Zulu
2 = A, B, C
3 = D, E, F
4= G, H, I
5 = J, K, L
6 = M, N, O
7 = P, Q, R, S
8 = T, U, V
9 = W, X, Y, Z