This unique hybrid works with your telephone to give you more control over interview recording and playback. The Inline Patch is a little box that connects between the base of an analog or cordless telephone and the wall jack. You can continue to talk on the phone and get access to audio on both sides of the call. The unit’s two back-to-back hybrids give you complete control of audio from both sides of the call. Audio input jacks let you mix sound bytes or music into your conversation. One stereo output jack provides your voice on one channel and the caller's voice on the other channel. A second output jack contains a mix of both voices. Front panel control for each output offers all the control you will need. The Inline Patch does not disrupt your Caller ID or ring signals.
http://www.coopradio.org/