[Asterisk-Users] Confusing Contexts using AMP

[Aaron Glenn]

I'm using Asterisk at Home with the AMP interface and I'm having troubles
getting incoming calls working properly. In AMP, I have it set to take
incoming calls from PSTN, during regular business hours, to be sent to
extension 201. The include statement for extentions-additional.conf is
uncommented in extensions.conf; and I've verified AMP successfully
changes the config files. However when I make a call I hear nothing,
and tailing the full log, I notice * loops with :

Feb  8 13:58:45 NOTICE[12001]: Got event 2 (Ring/Answered)...
Feb  8 13:58:45 VERBOSE[12001]:   == Starting Zap/2-1 at default,s,1
failed so falling back to exten 's'
Feb  8 13:58:45 VERBOSE[12001]:   == Starting Zap/2-1 at default,s,1
still failed so falling back to context 'default'
Feb  8 13:58:45 WARNING[12001]: Channel 'Zap/2-1' sent into invalid
extension 's' in context 'default', but no invalid handler

Why is it doing to the default context instead of from-pstn?

It goes without saying that I'm new to Asterisk and phone systems are
most definitely not my forte. Like any good OSS user I've tried
reading all that google will spit out at me, and the mailing list
archives. If it didn't search hard enough and this question has been
asked and answered before please except my apologies and point me in
the right direction.

Is there some sort of comprehensive list of contexts and the actions
that invoke them? They sound self explanitory, but from the wiki
documentation, it makes it seem like I can have any damn context I
want...? There's a major gap in my understanding of * innerworkings.

Regards,
aaron.glenn