Some device ESN contain LETTERS.  In this case, use the following sequence to represent that letter

HEX [A] enter [*][1][*]
HEX [B] enter [*][2][*]
HEX [C] enter [*][3][*]
HEX [D] enter [*][4][*]
HEX [E] enter [*][5][*]
HEX [F] enter [*][6][*]