Page 99 - Asterisk™: The Future of Telephony

Working with Interface Configuration Files

In this chapter, we’re going to build an Asterisk configuration on the platform we have
just installed. For the first few sections on FXO and FXS channels, we’ll assume that
you have a Digium TDM11B kit (which comes with one FXO and one FXS interface).
This will allow you to connect to an analog circuit (FXO) and to an analog telephone
(FXS). Note that this hardware interface isn’t necessary; if you want to build an IP-only
configuration, you can skip to the section on configuring SIP.
The configuration we do in this chapter won’t be particularly useful on its own, but it
will be a kernel to build on. We’re going to touch on the following files:

zaptel.conf
Here, we’ll do low-level configuration for the hardware interface. We’ll set up one
FXO channel and one FXS channel. This configures the driver for the Linux kernel.
zapata.conf
In this file, we’ll configure Asterisk’s interface to the hardware. This file contains
a slightly higher-level configuration of the hardware in the Asterisk user-level
process.
extensions.conf
The dialplans we create will be extremely primitive, but they will prove that the
system is working.
sip.conf
This is where we’ll configure the SIP protocol.
iax.conf
This is where we’ll configure incoming and outgoing IAX channels.
In the following sections, you will be editing several configuration files. You’ll have to
reload these files for your changes to take effect. After you edit the zaptel.conf file, you
will need to reload the configuration for the hardware with /sbin/ztcfg -vv (you may
omit the -vv if you don’t need verbose output). Changes made in zapata.conf will require
a module reload from the Asterisk console; however, changing signaling methods re-
quires a restart. You will need to perform an iax2 reload and a sip reload after editing
the iax.conf and sip.conf files, respectively.
In order to test the new devices we have defined, we must have a dialplan through which
we can make connections. Even though we have not discussed the Asterisk dialplan
(that’s coming up in the next chapter), we want you to create a basic extensions.conf
file so that we can test our work in this chapter.

Make a backup copy of the sample extensions.conf (try the bash command mv exten
sions.conf extensions.conf.sample), and then create a blank extensions.conf file (using
the bash command touch extensions.conf), and insert the following lines:

Working with Interface Configuration Files | 71