On landlines, how did the system know who was talking to who?

For example, 2 ppl on one side of the country try to talk to 2 ppl on the other side, all 4 ppl in separate houses But are all using the same telephone wires. How does my voice not get jumbled up when talking to the other person when there are multiple ppl using the same telephone wires at the same time?

like back even farther they had the operators that would disconnect and reconnect you to complete the line, but obviously nowadays we dont do that. When the operator disconnected you to connect to others, how didnt they disconnect everyone using that particular telephone wire?