H.323 ISDN Gateway (isdngw)
This ISDN gateway converts H.323 calls into ISDN audio calls. It does not handle H.320 video calls.
Currently the gateway only works with isdn4linux and not with the newer mISDN.
The gateway was originally written by Bertrand Croq.
|Version 0.4.0||Size||Unix tar archive|
|Source Code||40 KB||
|Version 0.3.5||Size||Unix tar archive|
|Source Code||40 KB||
|Linux Executable (static)||2 MB||
isdngw is a gateway between telephony on ISDN and telephony on IP
networks using H.323. It is based on OpenH323 and ISDN4Linux. The gateway uses ISDN to
make and receive calls but any type of phone (pots, mobiles...) can call and
This software is released under the GNU General Public
- make calls from H.323 endpoints on an ISDN line
- receive calls from an ISDN line and connect to H.323 endpoints
- conversion between H.323 user input strings and ISDN touch tones
- can register to a gatekeeper using prefixes
- filter authorized endpoint from their IP
- send the caller's phone number to the H.323 endpoint when receiving a
- can play a message to the H.323 endpoint while make an outgoing call
- more to come...
isdn2h323 has some least cost routing features but I have never
used it; the code is still here in isdngw but it has never been
isdngw is a PWLib application, with a standard PWLib Makefile.
You have to build PWLib and OpenH323 first (following their build instructions).
Then, move into the isdngw directory and do a make depend to
compute the dependencies. Now, you are ready to compile different versions of
- make opt builds the optimized and stripped version
- make debug builds the ready to debug version
- make optnoshared builds the optimized version statically
linked to PWLib and OpenH323 libraries
- make debugnoshared builds the debug version statically linked
to PWLib and OpenH323 libraries
The configuration is quite long and complete. It uses the PWLib
configuration files format with sections and key values (just like Windows
There are two such configuration files:
/etc/isdngw/isdngw.conf(the configuration of the gateway) and a
directory file (its path is given in isdngw configuration). The directory
file lists the associations between H.323 aliases and ISDN MSN, used when
isdngw's configuration file format
|admin = string
||The email address of the administrator.
|directory filename = string
||The path to the directory configuration file.
default value: no
|name = string
||The name of the gateway.
default value: ISDN
|status filename = string
||The path to an HTML file dynamically generated by the
gateway. This files gives the status of the different ISDN and some
|gatekeeper = string
||Address of the gatekeeper to use. If a gatekeeper is
needed (see "need gatekeeper") and this value is left empty, the
gateway tries to discover a gatekeeper on the network.
|listener interface = string
||Address of the network interface to use to listen for
incoming H.323 calls.
|listener port = integer
||UDP port used to listen for incoming H.323 calls.
|need gatekeeper = boolean
||Indicates if gatekeeper registration is mandatory. If
set to yes, the gateway will stop if there is a problem while
registering to the gatekeeper.
|ras interface = string
||Address of the interface used to communicate with the
gatekeeper. This value must be defined due to recent changes in
PWLib/OpenH323 libraries. If no value is given, the value is taken
from "listener interface".
|atd timeout = string
||Time to wait (in seconds) on the ISDN line to get an
answer when making a call.
default value: 30
|default msn = string
||The default phone number of the gateway that will be
sent when making calls. This value mustn't have any special prefix:
for example, in France, the first digit is not given because it
represents the phone operator used.
default value: none
|agc = boolean
||Indicates if automatic gain control must be used.
default value: no
|echo compensation = boolean
||Try to remove the echo before sending audio data to
the ISDN line.
default value: no
|traces = string
||The path of the log file, where the PTRACE() calls are
outputted. If the path is left empty, there is no output.
|level = integer
||The maximum trace level (from 0 to 5).
default value: 0
|This section contains a list of sound files played by
the gateway at different moments of the communications. The format of
these file is quite simple: these are raw 8000samp/sec. with 16bit
signed mono samples.
The easiest bay to build your samples is to use sox, for
sox inputfile.wav -t raw -r 8000 -s -w -c1 outputfile
|connecting = string
||Path to a file that is played when an H.323 endpoint
make a call through the gateway (until the call is answered). If no
file is given, the gateway is silent until it gets an answer from the
The format of the
|This section contains the list of the ISDN4Linux
devices to use. The name of the keys has no importance, but there
mustn't be two keys with the same name.
|Section [Allowed IP]
|This section contains the list of endpoint IP prefixes
that are allowed to use the gateway. Like in the previous section,
two keys mustn't have the same name but their name has no other
|This section contains the list of the phone prefixes
that the gateway handles. This is used when registering to the
gatekeeper, so that it can decide which gateway must be used when an
endpoint wants to call a phone. Like in the previous section, two
keys mustn't have the same name but their name has no other
There is a configuration sample in the download archive.
isdngw's directory file format
|number = integer
||The ISDN MSN associated with the alias given in the section
|The directory file is composed of sections with only
one key: number. Each section name is an alias to be associated with
the ISDN MSN given to the "number" key.
number = 1031
number = 1032
There is a sample directory in the download archive.
isdngw is a PWLib PServiceProcess application so it can be run as a daemon
or as a console application. To have some help, you can do isdngw
To start the gateway as a daemon, use isdngw -d, which will
return once it is started, and to stop the daemon you just have to do
isdngw -t (you have to wait a few seconds or more before it really
To start the gateway as a standard application, use isdngw -cx.
This way, you will get the system messages on the standard output.