AutoHybrid gives you simultaneous send and receive audio through analog telephone lines. Not just another half duplex auto-coupler, this is a full duplex AutoHybrid. Yes, you can send and receive audio at the same time. The dual transformer hybrid is capable of 20 dB nominal trans-hybrid loss. In other words, your transmit signal will appear mixed with the receive signal, but at a level 20 dB lower than it was sent into the phone line.