Why do phone calls sometimes drop in quality and stay in the reduced quality for the remainder of the call, but then if you hang up and re-dial the quality is back to normal?

Question

Edit: I am referring to mobile network local/national calls.

In: 9

Answer 1

It probably depends on your phone and network.

It helps to think about the phone data like streaming a movie. Even if you’re not really using data for the call, the way even wired phones transmit their data is close enough to data streaming we can just pretend they’re the same.

So when quality is good, all of the equipment making a connection between you and the other person is working well and you are streaming “fast”.

But maybe something goes wrong along the way. Some equipment may be overloaded, or maybe there’s some bad wiring somewhere in the network. That causes “loss”. Some equipment that’s part of the chain notices the “loss”. It responds by doing something to use less data. That usually means adding “compression”, which for voice data usually means cutting out some of the audio frequencies so each second of audio takes less data to transmit.

In a really sophisticated system like Netflix or Youtube and most internet infrastructure, the equipment will periodically switch back to “fast” mode just to see what happens. It might even try finding a way to send the data through a different route to see if that does better.

But phone networks are a weird mix of new and very old hardware. So some of it may not be set up to switch back and forth, and it may not be able to change the route the data takes once it finds a route. But if you hang up and redial, it might be likely the data takes a different route through different equipment and the new route is “faster” so compression doesn’t have to happen.