18.2. VoiceMail IMAP Integration

“Unified messaging” has been a buzzword in the telecommunications industry for ages. It’s all about integrating services together so users can access the same types of data in multiple locations, using different methods. One of the most touted applications is the integration of email and voicemail. Asterisk has been doing this for years, but many of the larger companies are still trying to get this right. Asterisk has had the ability to send users voicemails via email, using the Mail Transport Agent (MTA) in your Linux distro (this always used to be sendmail, but Postfix has become increasingly popular as an MTA). Voicemail to email is one of the oldest features in Asterisk, and it normally works without any configuration at all.^[186]

^[186] When we say “it works,” what we mean is that Asterisk will compose the email and submit it to the MTA, and the email will successfully be passed out of the system. What happens to it after it leaves the system is a bit more complicated, and will often involve spam filters treating the mail as suspect and not actually delivering it. This is not really Asterisk’s fault, but it’s something you’ll have to deal with.

Internet Message Access Protocol (IMAP) integration has existed in Asterisk (and been steadily evolving) since version 1.4. IMAP voicemail integration means your users can access their voicemails via a folder within their email accounts, which gives them the ability to listen to, forward, and mark voicemail messages with the same flexibility that the Asterisk VoiceMail() dialplan application gives. Asterisk will be aware of the statuses of those messages when the users next log in via the phone system.