Retronetworking » osmo-isdntap

h1. osmo-isdntap

@osmo-isdntap@ is a small stand-alone [daemon] program that you can run to create recordings of ISDN calls.

It is part of the [[retronetworking:]] project.

The program works by passively decoding the ISDN D-channel, specifically the Q.931 call control protocol.  Whenever a call is being set up, it starts to capture the B-channel

timeslot allocated to that call.  It creates two files, one for each of the two directions of the call.  The files contain the raw transparent binary B-channel data.

Currently the only supported ISDN hardware/driver interface is DAHDI.

Currently, only PRI (primary rate) ISDN interfaces are supported.

h2. git Repository

You can clone from the official osmo-isdntap.git repository using

<pre>

        git clone https://gitea.osmocom.org/retronetworking/osmo-isdntap

</pre>

There is a web interface at <https://gitea.osmocom.org/retronetworking/osmo-isdntap>

h3. Converting recordings to audio

If you'd like to convert any of the recorded files to audio, you can use the following example

command to do so:

<pre>

        sox --channels 1 --type raw --rate 8000 -e a-law isdntap-03012342111-03012343038-20221016-212558-8-tx.raw output.wav

</pre>

The generated `output.wav` file can then be played back with any standard audio player.