Connect THAT-2 between your telephone and handset for quick access to audio in and out of the telephone. The THAT-2 is used by radio stations to record and play sound bytes, and by TV and film sound crews to get IFB dialog over phone lines. The THAT-2 is the big brother of our model THAT-1, which is very popular with news reporters for its small yet rugged design. Over the years we’ve heard from many of our customers that they liked the THAT-1 but would prefer professional XLR jacks and compatibility with more telephone systems. Here is the answer... The THAT-2, a passive handset interface with professional and consumer jacks, separate input and output volume control, a selector switch for the different types of telephone systems, and still no batteries or AC needed. Simply unplug the handset coily cord form the base of your telephone and plug it directly into the THAT-2. Then, using the supplied cable, connect the THAT-2 back to the telephone. Now connect your audio equipment or powered speaker to the RCA or XLR jacks. The grey push button selects which audio will be sent into the telephone (OUT = talking on the handset, IN = sending audio in through the RCA jack). The output jacks contains a nice mix of the audio from both sides of the conversation, as well as the tones being pressed on the keypad. The THAT-2 has a three-position switch which accommodates electret, dynamic and carbon telephone handset microphone types. The THAT-2 will emulate the type of microphone that is in the handset and allow you to send audio into many different types of analog and digital PBX sets, as well as ISDN telephones. THAT-2 does not work with cordless or cell phones, or any telephone with a keypad in the handset.