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12 KiB

DAHDI Telephony Interface Driver
Asterisk Development Team <>
$Revision$, $Date$

DAHDI stands for Digium Asterisk Hardware Device Interface. This
package contains the user-space tools to configure the kernel modules
included in the package dahdi-linux.

Build Requirements
This package needs the headers from dahdi-linux. Thus you should install
dahdi-linux before building dahdi-tools.

Build System
GCC and friends. Generally you will need to install the package gcc.

Autotools (autoconf, automake and libtool) are needed if you clone from

Extra Libraries
Some libraries are needed for extra utilities that are provided with

- libusb is needed for building astribank_hexload, needed for firmware
loading of the Xorcom Astribank.
- libnewt is needed to build the optional but useful utility dahdi_tool.
- libpcap is needed for building dahdi_pcap.
- pppd is needed to build the dahdi pppd plugin.

Note: If using `sudo` to build/install, you may need to add /sbin to your PATH.
# Only if you cloned from git:
autoreconf -i

make install
# To install some extra configuration files:
#make install-config

Build Tweaks
Partial Build/Install
There are some make targets that are provided to build or install just
parts of DAHDI:

. Build targets:
- make: Build DAHDI user-space programs and libraries.
- make docs: Generate some extra documentation files.
. Install targets:
- make install: Install everything
- make install-config: install configuration files

Installation to a Subtree
The following may be useful when testing the package or when preparing a
package for a binary distribution (such as an rpm package) installing
onto a subtree rather than on the real system.

make install DESTDIR=targetdir

This can be useful for any partial install target from the list above.

Options For ./configure
The configure script executes various tests and the build will depend on
their result. You can pass it --with options and variable settings, for

./configure --without-ncurses CC="gcc-4.10"

If you just want to recreate the same files without a full detection
run, use:


To re-run ./configure with the same parameters it was run with last
time, use:

./config.status --recheck

Configuration for DAHDI resides under /etc/dahdi .

The main method to configure DAHDI devices is using the utility
*dahdi_cfg*. dahdi_cfg reads data from the configuration file
/etc/dahdi/system.conf , figures out what configuration to send to
channels, and send it to the kernel.

A sample annotated system.conf is included in this directory and
installed by default. Edit it to suit your configuration. Alternatively
use the script dahdi_genconf to generate one that should work with your
system. Note that while dahdi_genconf will generate a working configuration,
it will not automatically detect hardware echo cancellation modules. These
will have to be enabled manually in system.conf.

The configuration file of the dahdi init.d script is
/etc/dahdi/init.conf . That file is used to override defaults that are
set at the beginning of the init.d script.

Assigns span number and initial channel number for spans in each device.
Just like system.conf it may be generated with dahdi_genconf:

dahdi_span_assignments auto

It may also be edited manually to allow reserving span and channel
numbers for specific devices.

Theoretically, this file is similar to assigned-spans.conf. It allows
setting the type (E1/T1) of a "PRI" span. This cannot be configured
anywhere else: it needs to be done before the span is assigned as it
changes the number of channels the span has.

In practice most systems don't mix E1 and T1 and thus this file will
typically have at most a single wild-card line setting all cards to be
either E1 or T1.

Reference Configuration
Sample system.conf

Sample init.conf

Sample genconf_parameters
FIXME: still not properly formatted.


Sample assigned-spans.conf

Sample span-types.conf

The file zonedata.c contains the information about the tone zones used
in libtonezone (and hence also in dahdi_cfg). Here is a list of those zones:


DAHDI PERL modules
The directory xpp has, in addition to helper utilities for the
Xorcom Astribank, a collection of PERL modules to provide information
related to DAHDI. The PERL modules themselves are under xpp/perl_modules/ .
In xpp/ there are several utilities that use those modules:
- xpp-specific: dahdi_registration, xpp_sync, xpp_blink .
- General: lsdahdi, dahdi_genconf, dahdi_hardware, dahdi_drivers

The DAHDI PERL modules will currently only be automatically installed if you
happen to install the xpp directory. Those utilities require the PERL modules
to be installed, however they will also look for them in the directory
perl_modules, and thus can be run directly from the DAHDI source tree. For

./xpp/dahdi_hardware -v

To get usage information on a program, you can also use perldoc
(sometimes provided in a package separate from perl itself). For

perldoc ./xpp/lsdahdi

Some of them are specific for the Xorcom Astribank and described in its
documentation. the others are:

A somewhat glorified `cat /proc/dahdi/*`.
Generates configuration based on the existing DAHDI channels and on
/etc/dahdi/genconf_parameters (replaces genzaptelconf as well).
A two-liner script (not installed by default) that simply returns the
modules that should be modprobe-d on this system.
Uses the information from SysFS and its own knowledge to show
what PCI/USB DAHDI hardware is connected and if it is currently used
by a driver. Shows also some more information for Astribanks from
/proc/xpp .

PPP Support
DAHDI digital cards can provide data channels through PPP as
point-to-point connections. This requires a plug-in to the PPP daemon
that is included in the ppp/ subdirectory. To install it:

1. Make sure you have the PPP source / headers installed. On Debian:

apt-get install ppp-dev

2. Run 'make' on the ppp subdirectory:

make -C ppp
make -C ppp install

3. Make sure your kernel has support for both PPP (which is common is
distribution kernels and for HDLC (much less common) - CONFIG_PPP and

This section documents the start up sequence of the DAHDI modules.

There are generally two options: explicit (using an init script) and
implicit (run from UDEV hook scripts).

The dahdi init scripts does the following tasks:

* Loading the module dahdi and any other module listed in
* For xpp (Astribanks) - some specific initializations. See
* Runs link:doc/dahdi_cfg.8.html[dahdi_cfg] after all modules were
* A number of other tools may need to be run:
** link:doc/fxotune.8.html[fxotune]
** dahdihpec_enable

Only at this point Asterisk (or any other user of DAHDI) can be run.

(Also known as "hot-plug" or "pinned-spans". This requires:

* dahdi >= 2.8.0
* Setting the module parameter auto_assign_spans of dahdi to 0
* (Recommended) Asterisk >= 12 - which supports "dahdi create channels".

When a device driver of a DAHDI device finishes initialization, it
creates a dahdi_device kernel object. A dahdi_device represents a single
DAHDI device (such as a PCI card) and may have several spans. If the
value of auto_assign_spans is 1 when dahdi_device is created, spans are
assigned automatically - each new span gets the first available span
number and range of channels. However if it is set to 0, spans will not
get assigned, and user space programs need to assign them. The
low-level interface for doing so is explained in the section "Span
Assignment" in the README of DAHDI-Linux.

New Devices
When a kernel object is created or destroyed, the kernel sends an event
to user space. Those events are normally handled by udevd. Configurations
for udevd ("udev rules") may be placed in /etc/udev/rules.d or
/lib/udev/rules.d. This package installs rules that instruct udevd to
run the script `/usr/share/dahdi/dahdi_handle_device` on each new
device, which runs all the scripts in `/usr/share/dahdi/handle_device.d`.
Those scripts will:

* If `/etc/dahdi/span-types.conf` exists, apply it to the device. It is
used for E1/T1/J1 settings. See
<<_sample_span_types_conf,sample span-types.conf>>.

* If `/etc/dahdi/assigned-spans.conf` exists, assign the span according
to it (if it is not specified there: don't assign it).
used for E1/T1/J1 settings. See
<<_sample_assigned_spans_conf,sample assigned-spans.conf>>.

* But if that file does not exist, assign the span to the first
available place.

This script mainly uses the commands
link:doc/dahdi_span_types.8.html[dahdi_span_types] and

DAHDI devices are listed under `/sys/bus/dahdi_devices/devices`.

If you want to disable running this script, add the following line to

New Spans
Once a span is assigned, a kernel object will appear for it. It will be
listed under its device. As a new kernel object was created, an event is
sent to udev.

The standard DAHDI udev rules instruct udevd to run the script
`/usr/share/dahdi/dahdi_span_config` which runs all the scripts in
`/usr/share/dahdi/span_config.d`. Those script configures the new

* If system.conf does not exist, generates a temporary configuration
for the span using link:doc/dahdi_genconf.8.html[dahdi_genconf

* Runs link:doc/dahdi_cfg.8.html[dahdi_cfg] on the new span (using `-S`
and -C`).

* Runs `asterisk -rx 'dahdi create channels'` to add the new channels
and spans to Asterisk (if they were configured in advance).

If you want to disable running this script, add the following line to

New Channels
DAHDI channels have their own representation in the kernel. The standard
udev rules that dahdi-tools includes for them, however, don't run a
script for each device. Each DAHDI channel creates a block device file
at /dev/dahdi/chan/'span'/'rel-chan', where 'span' and 'rel-chan' are
each three-digit numbers (e.g: 035). 'span' is the span number and
'rel-chan' is the channel number relative to the span.

The udev rules generate the following extra symlinks under /dev/dahdi:

* /dev/dahdi/'num' - the channel number. As it was originally (but
continues beyond 250).
* /dev/dahdi/devices/'hardware_id'/'rel-span'/'rel-chan' - if the DAHDI
device has a hardware ID field, provide listing of the device's span
and channels.
* /dev/dahdi/devices/@'hardware_id'/'rel-span'/'rel-chan' - likewise for
the connector field. It has a "@" prefix.


This package is distributed under the terms of the GNU General Public License
Version 2, except for some components which are distributed under the terms of
the GNU Lesser General Public License Version 2.1. Both licenses are included
in this directory, and each file is clearly marked as to which license applies.

If you wish to use the DAHDI drivers in an application for which the license
terms are not appropriate (e.g. a proprietary embedded system), licenses under
more flexible terms can be readily obtained through Digium, Inc. at reasonable

Reporting Bugs
Please report bug and patches to the Asterisk bug tracker at[] in the "DAHDI" category.

-[] - The Asterisk PBX
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