[Asterisk-Users] Cisco Callmanager & Asterisk for Voicemail revisited

[Shaun Ewing]

Some of you may remember back in May the thread on using Asterisk as a
voicemail server for a Cisco Callmanager system.

My own Callmanager system is integrated into an Asterisk server for
voicemail (and other things). Back in May I was using H323 for
integration, but since I've upgraded to CCM 4.1 I have switched over
to SIP.

The integration with H323 required using Call forwarding to send the
call to an extension on Asterisk. For example, extension 7443 would
forward to 27443 on Asterisk which looked something like:
exten => _27XXX,1,Voicemail(u${EXTEN:1})

Obviously setting this for each and every phone on Callmanager was not
an option for any wide deployments, and Paul Davidson investigated
some of the other options. Paul discovered that it was possible to
setup a voicemail pilot, tick the voicemail box, etc. but you would
lose the ability to have the caller ID information added to the
voicemail.

This wasn't an option for us, as caller ID is quite important.

Up until now, I have continued with the custom extension option,
setting up the appropriate call forwarding when new phones were added
to the system. The trunk between CCM and Asterisk changed to SIP after
the CCM upgrade, but everything else stayed the same until I revisited
this today.

To summarise what I have accomplished:

Full voicemail integration between CCM and Asterisk with the following features:
- MWI
- Voicemail on the CCM side is enabled by selecting Forward to
'Voicemail' rather than yucky custom extensions. Allows for wide
deployment.
- Messages are accessed by pressing the 'Messages' button on the CCM
phones, or dialing the VM pilot number.
- If a CCM user doesn't want to take a call, they can press the
iDivert softkey to send to voicemail immediately.
- CCM users can forward all calls to voicemail in the ccmuser pages,
or by pressing CFwdAll and entering the pilot number or messages.
- All the standard Asterisk voicemail features work just fine, eg: vm to email.
- more

Bugs with the setup:
- If there's a SIP device registered with the Asterisk machine
handling the voicemail, and the call path is something like: Sip
Device -> Asterisk -> CCM. If the call subsequently reaches voicemail,
Asterisk prompts for proxy authentication and CCM drops the call. This
problem can be avoided by using usernames that don't match the caller
id, eg: [sip7345], or having a machine dedicated to Voicemail.
- That's all I've found

These options have been tested with Asterisk 1.0.8 and CCM 4.1(2)sr1.
If this is something that people would be interested (and you made it
this far), I'd be quite happy to whip up some instructions and add it
to the wiki.

-Shaun