How do phone companies move landline numbers when a business relocates from one address to another within the same exchange? Did a business, say in the 1960s or 1970s, have to change numbers when moving to a different location?
In: Technology
Telephony at the head end is mostly digital these days.
When you move your phone number is re-assigned to a new digital circuit attached to your local phone exchange.
If you use a landline this has to be turned from a digital signal to an analog one. The phone number is assigned to an analog port that becomes the physical phone wire going to your house.
These connections are called punch downs and are made manually inside of one of the pedestal boxes in your neighborhood that belongs to the phone company.
In the old days when everything was analog the phone number was physically punched line by line through exchanges to your business. The exchange itself was a gigantic mechanical devices that would accept an incoming call on a number and then make the physical connection.
Even before that switchboard were used where a physical person would manually make the connection when you were making a call.
For businesses it’s even easier because they will use a digital hardline for phones like a T1. This is a digital signal over an analog phone cable, and is 1.5mb/s per second. This translates to 24 phone lines (23 plus control signal if you want to be pedantic)
When you move a new T1 line is setup at the new building and a cutover occurs where the phone company moves the phone numbers assigned to your business to the new T1. You then plug in your phone system and Bob’s your uncle.
Today T1s are falling out of favor in exchange of internet based services like SIP trunking. With these it’s even easier. The businesses telephone system makes a connection to an internet based service offered by the phone company. Often you don’t even need to move the phone number, the phone system will know what to do when it’s plugged in at the other end.
When phones were brand new, the latest and greatest technology, each house with a phone would be connected by a wire. You’d call the exchange, tell the person who you wanted to talk to, and they would physically plug in a wire into the right holes in a big panel (the switchboard). Then you’d have a direct wire from your house to the other person – until the call ended, and they unplugged the connection at the switchboard.
Later, these human switchboard operators were replaced with a machine to do the same job. You’d dial a phone number identifying who you wanted to talk to, and the switchboard would automatically make an electrical connection between you and the right person.
Later, it became possible to change the mapping between “phone number” and “wire”, so a business could keep their phone number when they moved. The switchboard machine (or maybe computer) would just have to have its information updated.
Gradually, as things became more computerised, and phone lines started to carry internet as well, phones became internet destinations, and the mapping was from phone number to phone (instead of to wire). But we’re well beyond the 60’s and 70’s by that stage.
Well they also did it for residential. I remember moving and since it was within the same exchange we were able to keep the same number.
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