Hi PF, please could someone help explain how the bandwidth of a telephone line works. I have read that fibre optics uses light which has a high frequency and therefore can offer a high bandwidth versus a standard telephone line. But what I don't understand is the bandwidth of a standard telephone line. I understand that standard telephone lines use electrical pulses instead of light pulses but why are electrical pulses limited in terms of bandwidth? I didn't know electrical pulses had a frequency in the sense that radio and light waves do? To be a bit clearer. To send a digital pulse of light requires a range of frequencies and since light operates at a high frequency it can deliver large amounts of digital data quickly. If you send an electrical pulse down a telephone then surely this also requires a range of frequencies but a range of frequencies of what exactly? I didn't know electrical signals had a frequency since they are not electromagnetic radiation in the sense that light and radio waves are. Many thanks for any help offered!!