a modem
That's simple an A/D converter chip.
MODEM:A modem takes digital signal from computer and converts them to analog for the phone and reconverts them back
it is an DAC (Digital to analogue converter
no it dont
yes
Actually you have this backwards, the telephone lines can only carry analogue signals (voice band, 20Hz to 3KHz) not digital signals.The device that converts digital signals to analogue signals for transmission over telephone lines is called a phone MoDem(this stands for phone modulator demodulator). At the opposite end of the line it of course converts the telephone analogue signals back to digital signals.
Digital signal is moreefficientimmune to noiseerror freethan analog signal.
Analog instrument are interface with digital instrument with the help of analog to digital converter(ADC).ADC converts analog signals to digital signals.
A Demodulator (MODEM)
Terminal adapter.
Terminal Adapter
A modem converts the digital signals(used by computer)into analog signals(in telephones) and vice versa.
The set top box that your provider gives you is what converts the Digital signal to the analog signal. The digital signal is compressed at the provider and sent to the end user. The "tuner" (which can be built into a tv, a set top box or a cable card) Then decompresses the digital signal and converts it into an analog signal. There is much more to this did not know how technical you wanted your answer.