Need to pass alphabet DTMF

How can i pass alphabet DTMF in asterisk …

what is alphabet DTMF?

insted foe enetring the digits as dtmf…i have to enter the leters …

DTMF cannot represent letters, although there are conventions for mapping several letters onto each digit.

To me passing means taking the digit on input and sending it to the output unchanged, but maybe you really want a bit of dialplan code to map the letters into the corresponding digits?