Asterisk Documentation 1.2 README.misdn

mISDN Channel Driver for Asterisk PBX

This package contains the mISDN Channel Driver for the Asterisk PBX. It 
supports every mISDN Hardware and provides an interface for asterisk. 


* NT and TE mode
* PP and PMP mode
* BRI and PRI (with BNE1 and BN2E1 Cards)
* Hardware Bridging
* DTMF Detection in HW+mISDNdsp (much better than asterisks internal!)
* Display Messages to Phones (which support display msg)
* Screen/ Not Screen User Number
* Basic EchoCancellation 
* Volume Control 
* Crypting with mISDNdsp (Blowfish)
* Data (HDLC) callthrough 
* Data Calling (with app_ptyfork +pppd)
* Echo cancellation
* CallDeflection
* Some other

Supported Hardware:

chan_misdn supports any mISDN compatible Hardware.


- Fast Installation Guide
- Pre-Requisites
- Compilation 
- Installation
- Configuration
- Dial and Options String
- misdn cli commands
- mISDN Variables
- Debugging and sending Bugreports
- Examples
- Known working Configurations
- Known Problems
- Changes

Fast Installation Guide

It is easy to install mISDN and mISDNuser. Using the Makefile from
channels/misdn. You just need to type:

cd channels/misdn 
make misdn

Then all the necessary files are fetched from


To compile and install this driver, you'll need at least one mISDN Driver and
the mISDNuser package. Chan_misdn works with both, the current release version
and the development (svn trunk) version of Asterisk. mISDNuser and mISDN must
be fetched from

Please Note that mISDN works good for the linux-2.6.x kernels. Some of the
mISDN drivers do not compile against the 2.4.x or older kernels, you can patch
them, but than you'll get mysterious errors.

Using Kernels > 2.6.9 works perfect. 

Ok so far so good, now follow the compilation instructions.

!! Dont forget to create the /dev/mISDN device node.


The compilation of chan_misdn requires a library which will be generated under

To compile this library you just need to go into this directory and type
make. Now you can go back to the asterisk source root and type make install
again, which now should compile and install chan_misdn.


Chan_misdn is automatically installed by the asterisk installation process.

There is a sample init.d script for loading the mISDN modules (mISDN.sample),
5Asimply copy it to /etc/init.d/ and modify it, there you can enter your cards.

!! Forget to use capi together with chan_misdn. 


First of all you must configure the mISDN drivers. Each driver module has got
an options and layermask option, which tells the driver wether to start in
TE, NT, PP or PMP mode (there are lots more, please read docs in misdn for

After thinking about the above you'll probably want to configure the
misdn.conf file which resides in the asterisk config directory (normally

- misdn.conf: [general]
The misdn.conf file contains a "general" Section, and user sections which
contain misdn port settings and different Asterisk contexts.

The general section contains especially a variable named context with which
the default context is set. There is also the very important debug variable
which you can set from the Asterisk cli (command line interface) or in this
configuration file, bigger numbers will lead to more debug output. There's also a
tracefile option, which takes a path+filename where debug output is written

- misdn.conf: [default] section 
The default section is another special section which can contain all the
options available int the usr/port sections. the user/port section inherit
their parameters from the default section.

- misdn.conf: user/port sections
The user sections have names which are unequal to "general". Those sections
contain the ports variable which mean the mISDN Ports. Here you can add
multiple ports, comma separated. 

Espacially for TE-Mode Ports there is a msns variable. This variable tells the
chan_misdn driver to listen for incomming calls with the given msns, you can
insert a '*' as single msn, which leads in getting every incoming call (if
you want to share on PMP TE S0 with a asterisk and a phone or isdn card you
should insert here the msns which you'll like to give the Asterisk).  Finally
a context variable resides in the user sections, which tells chan_misdn where
to send incoming calls to in the Asterisk dial plan (extension.conf).

Dial and Options String

The dial string of chan_misdn got more complex, because we added more features,
so the generic dial string looks like:


The Optionsstring looks Like:

the ":" character is the delimiter.

The available Optchars are: 
	d - Send display text on called phone, text is the optparam
	n - don't detect dtmf tones on called channel
	h - make digital outgoing call
	c - make crypted outgoing call, param is keyindex
	e - perform echo cancelation on this channel, 
	    takes taps as arguments (32,64,128,256)
	s - send Non Inband DTMF as inband
	vr - rxgain control
	vt - txgain control

chan_misdn registers a new dial plan application "misdn_set_opt" when
loaded. This application takes the Optionsstring as argument. The Syntax is:


When you set options in the dialstring, the options are set in the external
channel. When you set options with misdn_set_opt, they are set in the current
incoming channel. So if you like to use static encryption, the scenario looks
as follows:

Phone1 --> * Box 1 --> PSTN_TE 
PSTN_TE --> * Box 2 --> Phone2

The Encryption must be done on the PSTN sides, so the dialplan on the boxes

* Box 1:
exten => _${CRYPT_PREFIX}X.,1,Dial(mISDN/g:outbound/:c1)

* Box 2:
exten => ${CRYPT_MSN},1,misdn_set_opt(:c1)
exten => ${CRYPT_MSN},2,dial(${PHONE2})

misdn cli commands

At the Asterisk cli you can try to type in: 

misdn <tab> <tab>

Now you should see the misdn cli commands: 

- clean
	-> pid 		(cleans a broken call, use with care, leads often
			 to a segmentation fault)
- send
	-> display	(sends a Text Message to a Asterisk channel, 
			 this channel must be an misdn channel)
- set
	-> debug	(sets debug level)
- show
	-> config	(shows the configuration options)
	-> channels	(shows the current active misdn channels)
	-> channel	(shows details about the given misdn channels)
	-> stacks	(shows the currend ports, there protocols and states)
	-> fullstacks	(shows the current active and inactive misdn channels)

- restart 
	-> port		(restarts given port (L2 Restart) )

- reload 		(reloads misdn.conf)

You can only use "misdn send display" when an Asterisk channel is created and
isdn is in the correct state. "correct state" means that you have established a
call to another phone (mustn't be isdn though).

Then you use it like this:

misdn send display mISDN/1/101 "Hello World!"

where 1 is the Port of the Card where the phone is plugged in, and 101 is the
msn (callerid) of the Phone to send the text to.

mISDN Variables

mISDN Exports/Imports a few Variables: 

- MISDN_ADDRESS_COMPLETE : 	Is either set to 1 from the Provider, or you 
				can set it to 1 to force a sending complete.

Debugging and sending bug reports

If you encounter problems, you should set up the debugging flag, usually debug=1 
should be enough. the messages are divided in asterisk and misdn parts. 
Misdn Debug messages begin with an 'I', asterisk messages begin with an '*', 
the rest is clear I think. 

Please take a trace of the problem and open a report in the Asterisk issue
tracker at in the "channel drivers" project,
"chan_misdn" category. Read the bug guidelines to make sure you
provide all the information needed.


Here are some examples of how to use chan_misdn in the dialplan (extensions.conf): 

OUT_PORT=1 ; The physical Port of the Card
OUT_GROUP=ExternE1 ; The Group of Ports defined in misdn.conf

exten => _X.,1,Dial(mISDN/${OUT_PORT}/${EXTEN})
exten => _0X.,1,Dial(mISDN/g:${OUT_GROUP}/${EXTEN:1})
exten => _1X.,1,Dial(mISDN/g:${OUT_GROUP}/${EXTEN:1}/:dHello)
exten => _1X.,1,Dial(mISDN/g:${OUT_GROUP}/${EXTEN:1}/:dHello Test:n)

In the last line you will notice the last argument (Hello), this is sended
as Display Message to the Phone.

Known working configurations

In this section I'll put working configurations for chan_misdn. Beware It
seems that between Kernel 2.6.3 and Kernel 2.6.8 there were lots of mISDN
Bugs. I use Kernel 2.6.9 now, it works quite ok, Kernel 2.6.10+ has changed
the pci_find_subgsys funktion, so hfc_multi from mISDN doesn't compile against
it, you can just change pci_find_subsys to pci_get_subsys, this works.

- chan_misdn-0.2.1
	* linux-kernel >= 2.6.8 (but at least 2.6) 
	* asterisk >= v1.2 , also CVS Head
	* mISDN/mISDNuser (3.0) from

Known Problems

* When I use mISDN->IAX I cannot make Trunk calls

-> You need to use ztdummy as dummy zaptel interface for the iax timing in
trunking mode, simply grab libpri, zaptel and compile them (i think you need
to modify the makefile in zaptel to add ztdummy to the defaultly compiled
modules) then modprobe ztdummy, this resolves the problem.

* I cannot hear any tone after succesfull CONNECT to other end

-> you forgot to load mISDNdsp, which is now needed by chan_misdn for switching
and dtmf tone detection

* I have strange ISDN behavior: sometimes I hear the other end, sometimes
not. Also I get STATUS Events with cause 100, with misdn debugging

-> Please update to newest version of chan_misdn and set the te_choose_channel
option in misdn.conf to yes

in the Changes File

Created by: josiahbryan, Last modification: Tue 30 of Sep, 2008 (14:45 UTC)
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