Page 341 - Asterisk™: The Future of Telephony

ways of doing this that can be very useful in larger, distributed networks, or environ-
ments where tighter integration with external applications is desired.

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
This downloads the source code. Extract it with:
# tar zxvf imap.tar.Z

You’ll want to pay special attention to the name of the directory that is
created by this command, as the directory name will probably change
again by the time you read this. During the production of this book, the
directory name has changed four times. The last time we checked, it was
named /usr/src/imap-2006h.

Navigate into the resulting folder and run:

# make lrh IP6=4

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