Does pulses in telephone copper wire count as frequncy? Are pulses in telephone copper wire count as frequncy? When we use DSL we use frequncies above 4khz because 0 to 4khz is reserved for telephone communications. From my childhood I remember my teacher said telephone uses pulses, if telephone uses electrical pulses and DSL uses frequency so how is that possible on a cable? I searched on google that if it is even possible to transfer frequncies over telephone copper wire but no chance to find something to clear it out. Please clear these terminologies and technologies to me. Thanks in advance.

Sounds are vibrations in the air at various frequencies. Voice can be reproduced at or below 3.4 KHz. Telephony simply changes the sound vibrations into electrical pulses at the same frequencies. The copper wire can carry even higher frequencies, too., and that can be used for data.

Disparate frequencies do not interfere with each other. That is how radio can have multiple radio stations because they are all operating at different frequencies. I suggest asking such basic electronics on Electrical Engineering.