Wait no longer! Build yourself a little circuit to change the analog phone’s audio to regular line audio to record with your sound card.

We started out with an old modem and ended up with a useful circuit to convert phone audio to regular line audio. This little hack is useful for those of us wanting to record Voip telephone calls ...

To begin with, he used off-the-shelf subscriber line interface circuits (SLICs) to implement the correct voltages, currents and impedances to drive analog phones.