This section describes how to configure the telephony hardware on a Wazo server.


Currently Wazo supports only Digium Telephony Interface cards

The configuration process is the following :

At the end of this page you will also find some general notes and DAHDI.

Notes on configuration files


A span is created for each card port. Below is an example of a standard E1 port:


Each span has to be declared with the following information:

  • spannum : corresponds to the span number. It starts to 1 and has to be incremented by 1 at each new span. This number MUST be unique.
  • timing : describes the how this span will be considered regarding the synchronization :
    • 0 : do not use this span as a synchronization source,
    • 1 : use this span as the primary synchronization source,
    • 2 : use this span as the secondary synchronization source etc.
  • LBO : 0 (not used)
  • framing : correct values are ccs or cas. For ISDN lines, ccs is used.
  • coding : correct values are hdb3 or ami. For example, hdb3 is used for an E1 (PRI) link, whereas ami is used for T0 (french BRI) link.
  • crc4 : this is a framing option for PRI lines. For example it is rarely use in France.

Note that the dahdi_genconf command should usually give you the correct parameters (if you correctly set the cards jumper). All these information should be checked with your operator.


This file contains the general parameters of the DAHDI channel. It is not generated via the dahdi_genconf command.


This file contains the parameters of each channel. It is generated via the dahdi_genconf command.

Below is an example of span definition:

switchtype = euroisdn
signalling = pri_cpe
channel => 1-15,17-31

Note that parameters are read from top to bottom in a last match fashion and are applied to the given channels when it reads a line channel =>.

Here the channels 1 to 15 and 17 to 31 (it is a typical E1) are set:

  • in groups 0 and 11 (see DAHDI interconnections)
  • in context from-extern : all calls received on these channels will be sent in the context from-extern
  • and configured with switchtype euroisdn and signalling pri_cpe


Check IRQ misses

It’s always useful to verify if there isn’t any missed IRQ problem with the cards.


cat /proc/dahdi/<span number>

If the IRQ misses counter increments, it’s not good:

cat /proc/dahdi/1
Span 1: WCTDM/0 "Wildcard TDM800P Board 1" (MASTER)
IRQ misses: 1762187
  1 WCTDM/0/0 FXOKS (In use)
  2 WCTDM/0/1 FXOKS (In use)
  3 WCTDM/0/2 FXOKS (In use)
  4 WCTDM/0/3 FXOKS (In use)

Digium gives some hints in their Knowledge Base here :

PRI Digium cards needs 1000 interruption per seconds. If the system cannot supply them, it increment the IRQ missed counter.

As indicated in Digium KB you should avoid shared IRQ with other equipments (like HD or NIC interfaces).