As DTMF from a radio,
*3(node#) connects in full transcieve.
*2(node#) connects in monitor mode / just listen
*1(node#) disconnects from the node
Your audio levels must be set correctly to decode dtmf.
You might watch it if you are having issues by typeing
asterisk -rvvv
from a OS command line and exit to return to the OS command prompt.