With my recent posts on the Public Switched Telephone Network (PSTN) I've been getting some email questions and suggested posts. I've received a few questions on telephones (what I would call end user devices) so I thought I'd take a few posts to describe how a basic telephone works.
The basic telephone set connected to the telephone network we are all very comfortable with using, has 4 basic functions:
- To provide a signal to the telephone company that a call is to be made (off-hook) or a call is complete (on-hook).
- To provide the telephone company with the number the caller wishes to call.
- To provide a way for the telephone company to indicate that a call is coming in or ringing.
- To convert voice frequencies to electrical signals that can be transmitted at the transmitter and convert those electrical signals back to voice frequencies at the receiver.