[Asterisk-Users] Unknown numebrs to a context/extension

[Matt]

What do I need to do to route all incoming calls on unknown numbers to
a certain context?  I know how to do the routing and setup the
context... but what do I actually have to do?  Right now if I call a
number on my PRI that is not setup in Asterisk I get a fast busy
signal.. I'd like it to go to a recording instead... but how to make
Asterisk answer any unknown number from pstn and direct it to a
context/extension?