The optimized inductive coil within the device creates a strong power for earpiece.
We manufacture some special accessories for connecting to the majority of mobile phones or sth like this. among them are Induction NeckLoop or Blue-Tooth Transmitters kits, GSM Card and Pen, and so on.
Auto answer, two-way talk, 50-80 cm to earpiece loud sound
They converts output into an inductive signal which is received earpiece,it doesn't influence it's previous function. For example mobile phone can listen and talk.