asterisk users - Jul 2005 - List extension in directory without mailbox?

I'm sure this is easy and I'm missing something, but how can I add an  
extension into the directory command (ie get's it's list of  
extensions from voicemail.conf) yet have no voicemailbox for the  
extension?

Basically I have an extension that gets forwarded onto somebody  
cellphone where they use their own voicemail.  I'd like to be able to  
list them in the company directory however.

I could do it with a dial that waits for more time than the users  
voicemail on his cellphone.  IE cellphone will always pickup first,  
but there must be another way?

-bill
wlloyd@slap.net