Error Prevention
Improving Connection Quality (Many types of noise such as echoes, white noise, jitter , harmonic distortion can be caused by poorly maintains equipment or poor connections)
solution: return the communications equipment and redo the connections
Amplifiers are used on telephone lines to avoid attenuation throughout their length (analog: also noise gets amplified when the signal is amplified)
Repeaters are used on digital circuits. (digital: a repeater receives the incoming signal, translates it into a digital message, and retransmits the message ==> noise is not repeated)