System information

a primary rate interface (PRI), this will be a T1 in North America, a J1 in Japan, or an
E1 in pretty much the rest of the world.
Once you have established the type of PRI connection the telco has given you, there
are some further details that you will require in order to properly configure DAHDI
and Asterisk (e.g., whether the connection is ISDN or a CAS-based protocol). Again,
you will find these in Chapter 7.
DAHDI Drivers
The connections where some real localization will need to take place are those of analog
interfaces. For the purposes of configuring your Asterisk-based telephone system to
work best in a given locality, you will first need to specifically configure some low-level
aspects of the way the Digium card interacts with the connected device or line. This is
done through the DAHDI kernel driver(s), in a file called /etc/dahdi/system.conf.
In the following lines (taken from the sample configuration that you get with a fresh
install of DAHDI), you will find both the loadzone and defaultzone settings. The load
zone setting allows you to choose which tone set(s) the card will both generate (to feed
to analog telephones) and recognize (on the connected analog telephone lines):
# Tone Zone Data
# ^^^^^^^^^^^^^^
# Finally, you can preload some tone zones, to prevent them from getting
# overwritten by other users (if you allow non-root users to open /dev/dahdi/*
# interfaces anyway). Also this means they won't have to be loaded at runtime.
# The format is "loadzone=<zone>" where the zone is a two letter country code.
#
# You may also specify a default zone with "defaultzone=<zone>" where zone
# is a two letter country code.
#
# An up-to-date list of the zones can be found in the file zonedata.c
#
loadzone = us
#loadzone = us-old
#loadzone=gr
#loadzone=it
#loadzone=fr
#loadzone=de
#loadzone=uk
#loadzone=fi
#loadzone=jp
#loadzone=sp
#loadzone=no
#loadzone=hu
#loadzone=lt
#loadzone=pl
defaultzone=us
#
PSTN Connectivity, DAHDI, Digium Cards, and Analog Phones | 187