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Since we’ve installed the table required for voicemail in the MySQL database, it is pos‐
sible to create mailboxes there without any other configuration. It is, however, also
possible to create mailboxes in an /etc/asterisk/voicemail.conf file (this file also allows
you to change various other default settings). We’ll continue to use the database to
create and manage users, since it is far more suited to the task, but we’ll also explore
the configuration file so that you can get a sense of the flexibility possible with Aster‐
isk’s voicemail.
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Chapter 8: Voicemail
The voicemail.conf file contains several sections where various default parameters can
be adjusted. For the most part, you won’t need to change any of these; however, you
should take a look at the ~/src/asterisk-1.15.<your version>/configs/samples/voice‐
mail.conf.sample file. It contains useful information about various options that can be
adjusted.
We have provided a simple voicemail.conf file next. If you wish to tweak the basic
configuration beyond this, simply add or edit the relevant option.
An Initial voicemail.conf File
We recommend the following sample as a starting point. You can refer to ~/asterisk-
complete/asterisk/11/configs/voicemail.conf.sample for details on the various settings.
Place the following in a file named /etc/asterisk/voicemail.conf:
; Voicemail Configuration
[general]
format=wav49|wav
serveremail=voicemail@shifteight.org
attach=yes
skipms=3000
maxsilence=10
silencethreshold=128
maxlogins=3
emaildateformat=%A, %B %d, %Y at %r
pagerdateformat=%A, %B %d, %Y at %r
sendvoicemail=yes ; Allow the user to compose and send a voicemail while inside
[zonemessages]
eastern=America/New_York|'vm-received' Q 'digits/at' IMp
central=America/Chicago|'vm-received' Q 'digits/at' IMp
central24=America/Chicago|'vm-received' q 'digits/at' H N 'hours'
military=Zulu|'vm-received' q 'digits/at' H N 'hours' 'phonetic/z_p'
european=Europe/Copenhagen|'vm-received' a d b 'digits/at' HM
Setting up a Linux server to handle the sending of email is a Linux
administration task that is beyond the scope of this book. You will
need to test your voicemail-to-email service to ensure that the
email is being handled appropriately by the Mail Transfer Agent
(MTA),2 and that downstream spam filters are not rejecting the
messages (one reason this might happen is if your Asterisk server is
using a hostname in the email body that does not in fact resolve to
it).
2 Also sometimes called a Message Transfer Agent.
The voicemail.conf File
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You can create a massive and complex voicemail.conf file (and can even store user
mailboxes in it), but we’re going to focus on a few curated examples to keep things
simple. You’ll likely find that what we present will serve your needs quite well (and
that the documentation samples will provide more detail, should you require it).
The [general] Section
The first section of the voicemail.conf file, [general], allows you to define global set‐
tings. Many of these settings can be assigned on a per-mailbox setting. We’ve listed in
Table 8-1 a few settings that we feel are the most important to consider.
Table 8-1. [general] section options for voicemail.conf
Option
format
Value/example
wav49|gsm|wav For each format listed, Asterisk creates a separate recording in that format
Notes
whenever a message is left. The benefit is that some transcoding steps may be
saved if the stored format is the same as the codec used on the channel. We like
WAV because it is the highest quality, and WAV49 because it is nicely compressed
and easy to email. We don’t like GSM due to its scratchy sound, but it enjoys some
popularity.a
When an email is sent from Asterisk, this is the email address that it will appear to
come from.b
If an email address is specified for a mailbox, this determines whether the message
is attached to the email (if not, a simple message notification is sent, and the user
will need to call into voicemail to retrieve their messages).
By default, Asterisk only allows a maximum of 100 messages to be stored per user.
For users who delete messages, this is no problem. For people who like to save
their messages, this space can get eaten up quickly. With the size of hard drives