System information

The voicemail server will need an extensions.conf file containing the following:
[voicemailbox]
; direct incoming calls to a mailbox
exten => Deliver,1,NoOp()
same => n,Set(Mailbox=${SIP_HEADER(X-Voicemail-Mailbox)})
same => n,Set(MailboxContext=${SIP_HEADER(X-Voicemail-Context)})
same => n,VoiceMail(${Mailbox}@${MailboxContext})
same => n,Hangup()
; connect users to their mailbox so that they can retrieve messages exten =>
Retrieve,1,NoOp()
same => n,Set(Mailbox=${SIP_HEADER(X-Voicemail-Mailbox)})
same => n,Set(MailboxContext=${SIP_HEADER(X-Voicemail-Context)})
same => n,VoiceMailMain(${Mailbox}@${MailboxContext})
same => n,Hangup()
sip.conf requirements
In the sip.conf file on the voicemail server, not only are entries required for all the
mailboxes for message waiting notification, but some sort of entry is required to define
the connection between the voicemail server and the rest of the SIP environment:
[VOICEMAILTRUNK]
type=peer
defaultuser=voicemail
fromuser=voicemail
secret=s0m3th1ngs3cur3
canreinvite=no
host=<address of proxy/registrar server>
disallow=all
allow=ulaw
dtmfmode=rfc2833
context=voicemailbox
The other end of the connection (probably your proxy server) must be configured to
pass voicemail connections to the voicemail server.
Running Asterisk as a standalone voicemail server requires some knowledge of clus-
tering and integration, but you can’t beat the price.
SMDI (Simplified Message Desk Interface)
The Simplified Message Desk Interface (SMDI) protocol is intended to allow commu-
nication of basic message information between telephone systems and voicemail
systems.
Asterisk supports SMDI, but given that this is an old protocol that runs across a serial
connection, there are likely to be integration challenges. Support in various PBXs and
other devices may be spotty. Still, it’s a fairly simple protocol, so for sure it’s worth
testing out if you are considering using Asterisk as a voicemail replacement.
Using Asterisk As a Standalone Voicemail Server | 177