My phone provider, AT&T, is soon going to retire their older 3G-based network in my area.
But their bold march to newer, better technologies has hit a minor snag. A few troublesome subscribers are still hanging on to their old phones.
It turns out I am one of those cheapskates. My five-year-old Android phone is plenty powerful for my needs, and I see no reason to pay another ransom for a new phone.
So, AT&T sent me a letter saying they would upgrade me for free to a newer phone. They are mailing me the new phone.
Is my phone really so outdated that it can't use the new network? Read on if you want to know the full story.
Circuit-switched calls
In the olden days, when dinosaurs roamed the earth, phones didn't need batteries. They were fixed to the wall. A wire connected them to the telephone exchange.
When you called anyone's number, an operator physically made connections to create a complete end-to-end circuit from your phone to their phone. When you hung up, the operator disconnected this circuit.