a telephone
A modem allows data to be transferred over a telephone line. It is a combination of MOdulate - DEModulate. One device modulates a digital signal from the computer into an analog signal for the telephone line, then the other device demodulates the signal back into digital for the receiving computer.
A softswitch is a device that is used for telecommunications. It is short for software switch and it allows connection from one telephone line to another.
A modem.
You've answered your own question. The device is called a Modem (Modulator demodulator).Some computers needed a separate device, later ones had the modem built in and only needed a telephone cord, between the computer and the phone socket.These days broadband is used. The computer's Local Area Network (LAN) socket is connected through a device called an ADSL (Asynchros Digital Subscriber Line) Router.This needs to connect through a filter to the telephone line, to stop interference on the telephone, which can be used at the same time.
The only telephone device that was used in the 1960's, was the land line telephone.
A modem allows your computer to connect to a phone line.
fax
MODEM (Modulator - Demodulator) allows communication between computers.Generally Modem connects to ISP over analog telephone line and further ISP connects to Computers over Internet.
Interrupt
Interrupt
a one line telephone means 1 person can talk at a time and a 2 line telephone means 2 separate people can talk at the same time in the same house
That's called a Modem... now superseded by broadband routers.