[asterisk-users] Dial plan constructions suggestions?

[Ed W]

Can I ask for some advice on dial-plan construction please

I have setup my dialplan to use 9 to get a zap trunk, leaving everything 
else for internal extensions.

However, this creates a problem in that my callerid is correct, but 
doesn't work to re-dial the incoming caller.  So if I simply click 
"missed calls" on my Snom phone and hit redial then it tries to dial an 
internal extension.

So I then setup Asterisk to add a "9" to the incoming callerid for all 
calls which come via the Zap trunk, but now this creates some issues 
with applications like Snapanumber and perhaps HudLite, which are trying 
to map the caller ID to numbers in the addressbook (and I don't really 
want my internal Outlook address books to have everyone listed with a 
"9" in front of their number)

How are others handling this?

I have considered simply dropping the prefix digit and working around 
any clashes in internal and external numbers (not very hard).

Grateful for any thoughts

Ed W