System information

The /etc/dahdi/system.conf file uses the hash symbol (#) to indicate a
comment instead of a semicolon (;) like the files in /etc/asterisk/.
Although it is possible to load a number of different tone sets (you can see all the sets
of tones in detail in zonedata.c) and to switch between them, in most practical situations
you will only need:
loadzone=uk # to load the tone set
defaultzone=uk # to default DAHDI to using that set
…or whichever tones you need for your region.
If you perform a dahdi_genconf to automatically (or should that be auto-magically?)
configure your DAHDI adaptors, you will notice that the newly generated /etc/dahdi/
system.conf will have defaulted both loadzone and defaultzone to being us. Despite the
warnings not to hand-edit the file, it is fine to change these settings to what you need.
In case you were wondering how we tell whether there are any voicemails in the mailbox
associated with the channel an analog phone is plugged into, it is done with a stuttered
dialtone. The format of this stuttered dialtone is decided by the loadzone/default
zone combination you have used.
As a quick aside, analog phones that have a message waiting indicator (e.g., an LED or
lamp that flashes to indicate there is new voicemail) achieve this by automatically going
off-hook periodically and listening for the stuttered dialtone. You can witness this by
watching the Asterisk command line to see the DAHDI channel go active (if you have
nothing better to do!).
That’s it at the DAHDI level. We chose the protocol(s) for PRI or BRI connections, the
type of signaling for the analog channels (all covered in Chapter 7), and the tones for
the analog connections that have just been discussed.
Once you have completed your configuration at the DAHDI level (in /
etc/dahdi/system.conf), you need to perform a dahdi_cfg -vvv to have
DAHDI reread the configuration. This is also a good time to use
dahdi_tool to check that everything appears to be in order at the Linux
level.
This way, if things do not work properly after you have configured
Asterisk to work with the DAHDI adaptors, you can be sure that the
problem is confined to chan_dahdi.conf (or an #included dahdi-chan-
nels.conf if you are using this part of the dahdi_genconf output).
188 | Chapter 9: Internationalization