Your code looked good:

if password[0]<>"1" Then goto error
if password[1]<>"2" Then goto error
...
if password[7]<>"8" Then goto error
menu:

error:



You can extend the Output_DTMF-routine to wait for the EOM-bit in the beginning.
And you can add some code in order to use this routine to play the other menu-messages, too.