asterisk users - Nov 2006 - special characters in alphanumeric extension s

>I use alphanumeric names as extensions in my Asterisk architecture, 
>which are the username part of the e-mail of each person at my site. 
>Because Asterisk was primarily built to use numeric extensions, I'm 
>having some problems with people that have usernames with dots between 
>letters, like "john.doe".
I ran into the same problem myself and I realized while making extensions
have some meaning other than a random number is neat and can be used for
tons of other purposes (notification emails for example), it quickly becomes
unmanageable if your org changes things around a lot like the one I work
for. Consider what would happen if a user changes their email address
(happens all the time: women get married etc) then there is the added
overhead of futzing with sip.conf etc in order to accomodate the change. 

In the end, I made the SIP account number & the voicemail box number the
last 4 digits of the user's DID, which greatly simplifies things. I also set
each user's email address as a local variable when the DID is lit up by the
PSTN, so my notification emails are a snap:

exten => h,1,System(echo "You hung up the call to " ${CALLERIDNAME}
| mail
-s ${EMAILADDRESS})

(note that the above is just an example I pulled out of my butt, probably
would not work in real life.)