Two-way intercom doorbell circuit

In rural areas, the courtyards are generally larger and it is inconvenient to call people outside the door. It is very useful to install a multi-functional intercom doorbell. When a guest of this kind of doorbell comes to visit,
as long as the button is pressed, the host can send out a music call signal . The host can pick up the receiver and the two parties can talk to each other. intercom doorbell