System information

a webcam for video calling, or perhaps an ability to load files from your desktop for
faxing.
Some of the disadvantages of softphones are the not-always-on nature of the devices,
the necessity to put on a headset each time you take a call, and the fact that many PCs
will at random times during the day choose to do something other than what the user
wants them to do, which might cause the softphone to stop working while some back-
ground task hogs the CPU.
ATAs have the advantage of allowing you to connect to your SIP network analog de-
vices,
§
such as cordless phones (which are still superior in many cases to more advanced
types of wireless phones
‖
), paging amplifiers, and ringers. ATAs can also sometimes be
used to connect to old wiring, where a network connection might not function
correctly.
The main disadvantage of an ATA is that you will not get the same features through
an analog line as you would from a SIP telephone. This is technology that is over a
century old.
With Asterisk, we don’t necessarily need to make the choice between having a soft-
phone, a hardphone, or an ATA; it’s entirely possible and quite common to have a
single extension number that rings multiple devices at the same time, such as a desk
phone, the softphone on a laptop, a cell phone, and perhaps a strobe light in the back
of the factory (where there is too much noise for a ringer to be heard).
Asterisk will happily allow you to interact with the outside world in ways that were
scarcely dreamed of only a few years ago. As we see more unification of communications
applications with the popularity of social networks, communities such as Skype, and
more focus on network-based services such as those provided by Google, the flexibility
and popularity of software-based endpoints will continue to grow. The blurring of the
lines between voice and applications is constantly evolving, and softphones are well
positioned to rapidly respond to these changes.
We still like a desk phone, though.
Configuring Asterisk
In this section we’ll cover how to create the sip.conf and iax.conf configuration files in
the /etc/asterisk/ directory, which are used for defining the parameters by which SIP
and IAX2 devices can communicate with your system.
§ An ATA is not the only way to connect analog phones. Hardware vendors such as Digium sell cards that go
in the Asterisk server and provide analog telephony ports.
‖ For a really awesome cordless analog phone, you want to check out the EnGenius DuraFon devices, which
are expensive, but impressive.
Configuring Asterisk | 87