Storing Voicemail in an IMAP Server




The ability to store voice messages in the same location as regular email is something
that the telecom industry  has been promising for a long time. They called it Unified
Messaging, and while most PBXes now offer some sort of unified messaging, it is typ-
ically very expensive to license and implement.
Naturally, Asterisk cuts through all the silliness and just allows you to have your voi-
cemailbox  integrated  into  an  IMAP  environment.  There  are  several  advantages  to
storing your voicemail on an IMAP  server.  When you listen  to  a  voicemail  on your
phone, the message is set to the read state on the IMAP server. This means that your

email client will also note that it has been read. By the same token, if you listen to the
message  from your email  client, the  voicemail will turn  off  the message notification
light on any phones that are assigned to that mailbox.  Deleting a message from one
place will cause it to be deleted from every place. So once deleted, the message is truly
gone. This is Unified Messaging, the holy grail of voicemail to email integration, but
Asterisk humbly decides not to make a big deal of it.
IMAP  integration is still new functionality, so there are a few things that need  to be
added  in order to get it  to function. First off, Asterisk needs to have an IMAP client
installed  so  that  it can  communicate  with the IMAP  server.  Pretty much  any  IMAP
server  works (even  Exchange Server),  and the authors  have  personally  tested IMAP
voicemail support with both the Courier-IMAP and Dovecot IMAP servers. The IMAP
server may be on the same physical machine as the Asterisk installation, or it may be
on the other side of the globe. To be able to access the IMAP server, Asterisk requires
an IMAP client library. This library is the University of Washington’s free IMAP client,
named c-client. To install the c-client you simply need to navigate to your /usr/src di-

rectory and run the following commands:

# wget ftp://ftp.cac.washington.edu/mail/imap.tar.Z