How do phones know who to call?



I don’t understand how when I call someone the phone doesn’t call all the other phones or can pinpoint the exact one I am calling.

In: Technology

Because of phone numbers. A hundred years ago when you picked up the phone, it would go to a human operator that would physically plug in a wire to connect you to another phone. But when they invented phone numbers, it allowed automatic switches to know which phone line you wanted to be connected to. Now it’s all digitized, but your phone number is still a unique identifier if your phone line, different from all the other phone lines in the world.

Each phone has a unique number. This is not the “phone number” that you memorized, but the International Mobile Equipment Identity (IMEI). The IMEI number is registered with the local cell tower that it’s in contact with. The process of buying a cell phone matches the IMEI of the phone handset to the “phone number” provided by the cellular carrier. When you type the phone number, the telephone database is queried to find what IMEI is assigned to the number at the present time. Then the radio network finds where that IMEI is located, and connects you to the phone.

Your phone doesn’t know where the destination is. The telephone network does. Because the destination phone is registers itself the destination network on a specific cell tower or telephone exchange hard line.