Telephone - Hybrid 1 Digital mixer

The D&R Telephone Hybrid 1 (in the radio world also known as a telephone hybrid) is a professional, passive interface that bridges a standard analog telephone line (POTS) and a mixer. The device is manufactured by the well-known Dutch radio and broadcast specialist D&R Electronica.
The purpose of this hybrid is to easily and simply transmit live or record a telephone conversation between a caller and a radio presenter.

It works perfectly.
For a better impression see photos