If you call a phone number whose wires are shorted together, the call goes directly to message. If you call a phone number whose wires are not connected to phones/phone system, your phone gives you the sound you get when the phones of the person you're calling are ringing.
A good answer is easier with a clear question giving the make and model of everything. "The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw
