This simple telephone switching system is designed by Dr. Mustafa Kemal PEKER for training purposes. All responsibility is belong to user. Schematic and code is under GNU public licence. Cannot be used as commercially.
1) System contains 1 subscriber and 1 central
2) Central cannot call.
3) When subscriber hangs up, Central rings.
4) When central answers, ringing stops.
5) Conversation ends when one side closes the phone.
For simplicity you may use an old AT computer power supply which includes
12v and 5v. Have fun…..