So, if we in having issues in calling someone, sometimes I just turn on my airplane mode and then turn it off. After that it works good and fine, but how?
When you turn on your phone after having it turned off or having it in airplane mode, the first thing it does is turn on its little radio and shout at the top of its proverbial lungs, “HELLO?? IS ANYONE OUT THERE?? My ID number is <XXXXXXX>, I am subscribed with <cell phone company>, looking for service, please respond!”
If there are cell phone towers in the nearby area, they will all hear this shout. They will take down your phone’s ID data and run their databases to see if you are one of their customers. If any of the towers recognizes your phone, they will each answer back, “Yes, hello, I am Tower #<XXXXXXX>, I am ready to chat.”
Your phone hears the responses and does some math to determine which one seems to have the best connection. After making its selection, it will reach out to that tower and negotiate a connection. If that negotiation succeeds, you can start sending data to and receiving data from that tower. Typically, your phone will choose the best tower available.
If you’ve been roaming around a good distance, there is a chance that the tower your phone was previously connected to isn’t the best one you could be connected to. The towers are designed to detect when you get out of range and seamlessly hand over the job of talking to your phone as you roam, so you are always connected to a tower with decent signal without having to manually disconnect and reconnect at every hand-over, but you might not always get on the best one. By going into airplane mode and back out again, you close your connection with your current tower and start the process over from scratch. It is possible that by doing this, you may be cutting a connection to a suboptimal tower and be connecting to a better tower instead.
Turning on Airplane mode turns off the wireless radio (i.e. the cellular network connection). Turning it off again, restarts it. Essentially you are “restarting” the radio. Just like you would restart a wifi router when it starts performing badly.