Today mostly is all digital, some landlines came via 3G and 4G. And I’m doing the whole concept simplified.

Old times yes, it was all wires. Btw, calls between cities was hell. You pick the phone, says that want to talk with City B, City A operator telegraph to City B to connect you with then, if that connection exists then you will be connected to an operator to City B and then being able to “make the call” and sometimes there is a delay.

Your phone number is a code, when you call other code a computer listen to this code and search in a list “Ok, OP wants to talk with code 555” and if it matches, it makes the call and if not, says the error message.

Of course that’s in today terms, in the old times when you get your phone to call someone, a person promptly asks you “Want to make a call to who?” and it simply connects their wire to your wire manually.