A phone “rings” when its network indicates an incoming call and the phone thus alerts the user. For landline telephones, the call signal can be an electric current generated by the switch to which the telephone is connected. For mobile phones, the network sends the phone a message indicating an incoming call.
A telephone “ring” is the sound generated when there is an incoming telephone call. The term originated from the fact that early telephones had a ringing mechanism consisting of a bell and an electromagnetically-driven hammer, producing a ringing sound. The aforementioned electrical signal powered the electromagnet which would rapidly move and release the hammer, striking the bell. This "magneto" bell system is still in widespread use. The ringing signal sent to a customer's telephone is AC at 90 volts and 20 hertz in North America. In Europe it is around 60-90 volts AC at a frequency of 25 hertz.