A400M on DAHDI User Manual

           OpenVox Communication Co.Ltd


General Safety Instructions 
Test Environments 
Chapter 1 Overview 
1.1 What is Asterisk 
1.2 What is A400M 
Chapter 2 Hardware Setup 
2.1 Power supply 
2.2 Timing cable 
2.3 FXO and FXS modules 
2.4 Hardware setup procedure 
Chapter 3 Software Installation and Configuration 
3.1 Download 
3.2 Installation 
3.3 Configuration 
Chapter 4 Reference 
Appendix A Specifications 
Appendix B PIN Assignments

General Safety Instructions


  1. The computers that have A400M card installed must comply with  the country's specific safety regulations. 
  2. Only service personnel should go to install A400M card.
  3. Before installing A400M card, please unplug the power cord and remove the cover from your PC.
  4. For avoiding personal injuries and damages to your machine and  A400M card, make sure bracket of the card is secured to the PC's chassis ground by fastening the card with a screw. 
  5. Electrical Surges, ESD are very destructive to the equipment. To avoid it, make sure there is a low impedance discharge path from your computer to chassis ground.
  6. To reduce the risk of damage or injury, please follow all steps or procedures as instructed.

Test Environments

Kernel version: 2.6.18-238.12.1.el5
DAHDI: dahdi-linux-complete-current
Asterisk: 1.8.0
Hardware: OpenVox A400M 

Chapter 1 A400M Overview

1.1 What is Asterisk

The Definition of Asterisk is described as follows:
Asterisk is a complete PBX in software. It runs on Linux, BSD, Windows (emulated) and provides all of the features you would expect from a PBX and more. Asterisk does voice over IP in four protocols, and can interoperate with almost all standard-based telephony equipment using relatively cost-effective hardware. Asterisk provides Voicemail services with Directory, Call Conferencing, Interactive Voice Response, Call Queuing. It supports for three-way calling, caller ID services, ADSI, IAX, SIP, H323 (as both client and gateway), MGCP (call manager only) and SCCP/Skinny (voip-info.org).

                                                         Figure 1 Topology

1.2 What is A400M

OpenVox A400M delivers great voice quality in the telephony systems. With interchangeable FXS/FXO modules, it can eliminate the requirements for separate channel banks or access gateways. 
The A400M consists of two parts: the A400MM and the A400MS. The A400MM connects Mini PCI slot while the A400MS installs FXS/FXO modules. The A400MS contains 4 module banks. Each bank supports one analog interface. The module banks may be filled with up to 4 FXO or FXS modules enabling the creation of any combination of ports. Scaling of an analog card solution is accomplished by simply adding additional cards. 

A400M works well with Asterisk®, Askozia®, Elastix®, FreeSWITCH, PBX in a Flash, trixbox®, Yate and IPPBX/IVR projects as well as other Open Source and proprietary PBX, Switch, IVR, and VoIP gateway applications. 

Target applications

  • Channel Bank Replacement / Alternative
  • Small Office Home Office (SOHO) applications
  • Small and Medium Business (SMB) applications
  • Gateway termination to analog telephones/lines


  • Support Mini PCI type Ⅲ
  • Designed for low-power systems
  • Support AskoziaPBX system
  • Support VIA, PC Engines motherboard and AMD geode based motherboard
  • Support trixbox, Elastix and other based Asterisk distributions
  • Support GPL Software driver used with zapte and DAHDI

Chapter 2 A400M Hardware Setup

There are some points that should be paid attention to when setting up A400M.

2.1 Power supply

The board should be powered when any FXS module installed; please connect the power source with A400M board by a 4-pin power source connector. If all modules are red, it can be powered by MIMI PCI slot, external voltage is unnecessary. 

2.2 Timing cable

If you have just one card in the system, all channels on that card have already run under the same clock source, so timing cable is unnecessary. But if there are more than one card, using timing cable has some advantages. Before using the clock line, each card works on its own clock, therefore precision of the clock is limited; each card will send /receive voice data at different speeds. In voice usage, this small issue can be omitted, but in data communication such as Fax/Modem, it will cause big problem. Data loss will cause communication broken or fax broken. Timing cable will force all cards to work at the same clock source, send data at the same speed, as a result no data will lost. 
If you found J914 (input) and J915 (output) interfaces on the card, it means the card supports clock line, for the details, please refer to HERE.

2.3 FXO and FXS modules

FXO (Foreign eXchange Office) is the office end of the line, and FXS (Foreign eXchange Station) is the station end, there is so much difference between them, they can be identified by color, the former ones are red and the latter ones are green. FXO modules use FXS signaling while FXS modules use FXO signaling. A FXO module corresponds to four FXO interfaces which receive power (battery) and ring signals, and a FXS module corresponds to four FXS ports which provides power (battery) and generates ring signals.

2.4 Hardware setup procedure

  • Power off your PC, remember unplug the AC power cable
  • Assemble A400MM and A400MS correctly with a IDE flat cable
  • Set the jumpers which control modules
  • Insert A400MM into a Mini PCI slot of a server
  • Put timing cable correctly if necessary, for more details, please refer to HERE
  • Please plug PSTN lines into FXO ports and extension telephone lines into FXS ports before you have detected your PSTN line works well.
  • Fix the board by a screw
  • Power on PC

                                                          Figure 2 Hardware setup 


Caution: If any FXS module is setup, you should make power on. During the above processes, an ESD wrist strap is needed. Once power is on, you must not attempt to install or take down the board. Do not forget to connect PSTN lines into analog phones directly to make sure the lines and phones are available before insert the PSTN lines into FXO ports. After hard ware setup, it is time to install software.

Chapter 3 A400M Software Installation and Configuration

A400M supports DAHDI software driver on Linux. To make full use of A400M, you should download, compile, install and configure DAHDI and Asterisk.

3.1 Download

DAHDI software packages are available on OpenVox official website or Digium. Some patches should be made while the driver source is from Digium, therefore, it is recommended that downloading the DAHDI driver package from OpenVox official website. 
Gain DAHDI source package from OpenVox:
Get Asterisk software package from Digium official website: 
Execute the following commands in the directory /usr/src/ in generally, the former two below are used for downloading these two packages and the later two are for unzipping them. 

tar –xvzf asterisk-1.8.0.tar.gz 

3.2 Installation

1. Hardware detection

#lspci –vvvv

Check the outcome and confirm your system has recognized A400M. If it has been recognized, "Network controller" will be displayed in the output information like that:

                                                  Figure 3 Hardware detection

If A400M is not recognized by the system, you have to power off and take out the card, then try to insert it into other Mini PCI slot.

2. Software installation
Some dependencies are crucial. If any of them is absent, the software installation process would not go through successfully. Let's run "yum install XX" (XX stands for the dependency's name) to check the availability of dependencies.

#yum install bison

#yum install bison-devel

#yum install ncurses

#yum install ncurses-devel

#yum install zlib

#yum install zlib-devel

#yum install openssl

#yum install openssl-devel

#yum install gnutls-devel

#yum install gcc

#yum install gcc-c++

#yum install libxml2

#yum install libxml2-devel

Notice: If there is no kernel-devel source in the system, users should run the following command to install the kernel-devel to peer current kernel:

#yum install kernel-devel-`uname –r`

While if there is no matched kernel-devel found, you should download matched RPM package to install it, or execute the following command to update to the latest and stable kernel version:

#yum install kernel kernel-devel
After installed, please reboot your machine to apply the new kernel and install the dependencies. If the dependency has been installed, system indicates that nothing to do which means you could go to next one directly. Otherwise, the system will keep on installing it.

After install the dependencies, please change to the directory dahdi-linux-complete-XX (XX represents DAHDI version), then perform commands one by one to install DAHDI.

#cd /usr/src/dahdi-linux-complete-XX


#make install

#make config
Caution: If there is something wrong after "make", please refer to HERE. In the url link, the moderator introduces you a method how to patch. After patching, save your changes and exit. Then run "make" again, if successfully, you are going to install Asterisk. 
Please operate those commands to install Asterisk.

#cd asterisk-1.8.0



#make install

#make samples

Notice: " make samples" will install the standard sample configuration file in the directory /etc/asterisk. As a freshman, you should perform make samples, that is to say, it is unnecessary to perform make samples every time. Because once performed, it will cover the old sample configuration files you have installed.

3.3 Configuration

1.Driver loading
After compiling and installing DAHDI and Asterisk, please load the driver by running:

#modprobe dahdi

#modprobe wctdm opermode=CHINA


Notice: After running "modprobe dahdi" or "modprobe wctdm opermode=CHINA", there is not any indication information displayed if loaded normally and successfully. "wctdm" is the driver module name of A400M. "opermode" applies to FXO port and is invalid for FXS port, and you are allowed to take place of "CHINA" to other mode name which is available in the file: 

If there is any error, please trace the cause. Until all errors are clear up, you could execute "dahdi_genconf" again, and then go to the next step. By running "dahdi_genconf", it will generate /etc/dahdi/system.conf and etc/asterisk/dahdi-channels.conf automatically. Checking whether the generated files information agrees with your hardware setup, if not, you should modify to your specific requirements. Do not forget to confirm dahdi-channels.conf is included in chan_dahdi.conf, if not, run command: 
# echo "#include dahdi-channels.conf" >> /etc/asterisk/chan_dahdi.conf

FXO ports use FXS signaling, while FXS ports adopt FXO signaling. A part of system.conf which is one of the basic channel configuration files is displayed. 

                                           Figure 4  A part of system.conf

2. Country mode modification
In order to match your country pattern, you need to change parameters loadzone and defaultzone to your country. For example, your system is in CHINA, you would like them change to: 
loadzone = cn
defaultzone = cn

Notice: Some zonedata is available in the file ".. /dahdi-XX/tools/zonedata.c", you can refer to it to match your country mode. Meanwhile, you also need to modify another parameter which is in file /etc/asterisk/indications.conf.

A part of file /etc/asterisk/dahdi-channels.conf is showed as below. (Modification, if it is not agree with the hardware setup)

               Figure 5 A part of dahdi-channels.conf

After modifying the country mode, please execute the following command:

#dahdi_cfg –vvvvvv

The command is used for reading and loading parameters in the configuration file system.conf and writing to the hardware. A part of outputs are showed in the following figure.

                                                          Figure 6 Channel map

3. Asteriskinitiation

#asterisk -vvvvvgc

If Asterisk is already activate, run "asterisk –r" instead. In the CLI, please run the following command:
localhost*CLI> dahdi show channels

                                           Figure 7 channels show

If DAHDI channels are found, it means they have been loaded into Asterisk. You are going to edit dialplan by your requirements.


4. Dialplan edit
Users must make sure that the context "from-pstn" and "from-internal" are in extensions.conf, here a simple example is given:

#vim /etc/asterisk/extensions.conf

                     Figure 8 dial plan

Notice: You should write the destination number instead of the outgoing_number in the above dial plan. The dialplan achieves that when an extension telephone dials 200, Asterisk will transfer through channel 3 to the external destination. While a call comes from PSTN line, Asterisk answers firstly, and then gets through to the extension set which connects channel 1. 

After saving your dialplan, please run "asterisk –r", then execute "reload" in the CLI. Next you are able to make calls. 

Chapter 4 Reference

Any questions during installation please consult in our forum or look up for answers from the following websites:

Appendix A Specifications

• Weight and size

Weight: 14g(A400M)      (2.89oz)

              64g(A400MS)   (2.26oz)

Size: 44.6×59.6×1mm³ (A400MM)

        113×113×1.3mm³ (A400MS)

• Interfaces

Up to 4 ports through a combination o f FXS and FXO modules

4 RJ-11 interfaces on a single PCI bracket

Mini PCI type III

• Environment
Temperature: 0 ~50°C (Operation)                 -40 ~125°C (Storage)

 Humidity: 10 ~90% NON-CONDENSING 

 • Power consumption

Power:  1.8W Minimum,  11.6W Maximum 

 • Hardware and software requirements

RAM 128 + MB

 Linux kernel 2.4.X or 2.6.X

 CPU 800+ MHZ 

Appendix B PIN Assignments

Either 4-pin or 6-pin RJ11 port is compatible with A400M; let's illustrate pin assignments of RJ11 port by the following tables.

                     4-pin RJ11 port

4-pin RJ11 port




Not used









Not used

                      6-pin RJ11 port

6-pin RJ11 port




Not used



Not used









Not used



Not used