Monitoring a DAHDI or Zaptel Channel

Sometimes you need to listen to a DAHDI channel or listen to a Zaptel channel on an Asterisk box, here is how you do it.

If you need to listen to Zaptel Channel 1, then you would do:

# ztmonitor 1 -m -r rx.raw -t tx.raw

This will make two files, one for the received stream and one for the transmitted stream.

If you are on DAHDI, you can do:

# dahdi_monitor 1 -m -r rx.raw -t tx.raw

(exit both of them with CTRL-C when done)

Once you have these files, you can play it on the box you are on with

# play -r 8000 -s -2 -c 1 -t raw rx.raw
# play -r 8000 -s -2 -c 1 -t raw tx.raw

But usually you are on a server, in which case you might be wondering “how can I play a raw file?”. Well, luckily you don’t have to, you can just type:

# sox -r 8000 -s -2 -c 1 -t raw rx.raw rx.wav
# sox -r 8000 -s -2 -c 1 -t raw tx.raw tx.wav

And now you will have two files called rx.wav and tx.wav on your system that you can transfer to your laptop can play to your hearts content.

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Mikel