[Asterisk-Users] Troubles with voicemail and cisco 7905 SIP

[Lele Forzani]

I'm deploying a fairly large number of Cisco 7905 with SIP connected to an 
asterisk PBX.

The problem:

the 7905 has this nice "feature": You can set a "voice mail number" in 
configuration, so that you can listen your voice mail just by hitting the 
"messages" key on the phone. It just autodials "8500" or whatever else.
The customer wants this, so disabling it is not an option.

The phone also has another fine feature: when it is busy, not available, or 
has "do not disturb" mode set, it just sends out a "302 redirect" message to 
8500 or any "voice mail number".

So the caller gets the voicemailmain() prompt whenever he calls a busy/na 
7905.

What to do? The phone thinks you are using the same extension for both 
listening to your messages and leaving a new message, so I have to be able to 
understand from the exten => 8500 perspective if this exten has been dialled 
explicitly OR we have reched it because of a forward, and have a way to 
identify the original extension the call was directed to.

Perhaps, having chan_sip, or app_dial set a channel variable to store the 
original extension whenever they accept a 302 from an endpoint?

thanks
lele