asterisk users - Dec 2006 - Re: Match a Numer - then continue with, dialplan

I think you're making it far too difficult.

What I do is something like this:

[outgoing]
include => internal
include => longdistance
;Always include internal first, as matches from the first include
;will be used first. This allows you to make sure your internal
;extensions don't go out your trunks.

[longdistance]
ignorepat => 9;
include => default; already included from local, but putting here for 
clarity
include => local;

exten => _91XXXXXXX,1,Macro(trunkout,${EXTEN})     ;Medium Distance
exten => _91XXXXXXXXXX,1,Macro(trunkout,${EXTEN})  ;Long Distance

Then, I have:
[macro-trunkout]
exten => s,1,Set(cname=${DB(showname/${CALLERIDNUM})});
exten => s,n,Set(cnum=${DB(shownum/${CALLERIDNUM})});
exten => s,n,GotoIf($["foo${cnum}" = "foo"]?6);   //if
calling from ZAP
channel that set caller ID already
exten => s,n,Set(CALLERID(name)=${cname}|a);
exten => s,n,Set(CALLERID(number)=${cnum}|a);
exten => s,n,Dial(${TRUNK}/${ARG1:${TRUNKMSD}});
exten => s,n,Goto(s-${DIALSTATUS},1)

exten => s-ANSWER,1,Hangup
exten => s-CONGESTION,1,Congestion(30)
exten => s-CONGESTION,2,Hangup
exten => s-CANCEL,1,Hangup
exten => s-BUSY,1,Busy(30)
exten => s-BUSY,2,Hangup

Why is this important? It's not. But it is fundamentally different from 
what you're asking. You want to match a partial extension dialed and 
then continue appending digits. What you really need to do is wait for 
the whole number, then decide what kind of number it is, do the 
processing, and send it on its way. It's just a slight change in the way 
you're thinking, because you understand that there's a class of numbers 
to treat differently. And that's OK. Just don't do anything with it 
until the whole extension has been entered!

You'll notice that, anything not going through the trunkout macro 
doesn't get tweaked, and anything that goes through there will read from 
the database. I could just as easily set a single value, but I have some 
users that I want to go out as themselves, and different departments 
that have a general number, etc. I found the Asterisk Database to be the 
easiest to tweak, as I have some scripts to allow admins to change the 
effective CallerID on the fly.

I hope this helps! Asterisk can do what you're asking, and it does every 
day.