system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How can 1 strand of optic fibre hold more then one phone call at a time?
gpt
There are actually a few ways that this is accomplished, used simultaneously.  
   
One is "time division multiplexing".  Computers are able to process signals much, much faster than is required to recreate a human voice.  A voice call needs only about 8 kilohertz (8 thousand samples per second) to get reasonable quality.  Since computers are so much faster, they can simply transmit the bits from Conversation 1, then C2, then C3, ... eventually going back and transmitting the next bits from C1, then C2, etc. 
   
Another way is by "frequency multiplexing".  You take one stream of calls as described above and transmit it on one carrier frequency...one particular color of light.  You take another stream and transmit it on another color of light.  And so on.  Since you can send many, many colors simultaneously, you can transmit many streams of data on the same fiber.  And remember, each of those streams carries multiple phone calls.  
   
And finally, fiber optic cables used for telecommunications are rarely made of one strand; they are typically bundles of many strands.