Okay, so imagine you have a phone. Your phone number is like your name for your phone, which lets other people call you, text you, or send you messages. But sometimes, there are other numbers that your phone has that you might not know about. One of those numbers is called an MSISDN.
Now, an MSISDN is a really fancy code that's used to identify your phone. It's kind of like a secret code that only your phone and your phone company know about. This code is made up of different parts that tell your phone company important information about your phone, like what country you're in, what phone company you use, and what specific number is assigned to your phone.
So, let's say you're traveling to a different country and you want to use your phone there. Your MSISDN code will tell your phone company that you're not in your usual country and that you need to be connected to a different network. And your phone company can use that code to make sure that you stay connected to the right network and that you don't get charged too much for using your phone in a different country.
In summary, an MSISDN is like a secret code that your phone company uses to identify your phone and keep it connected to the right network, no matter where you are. It's kind of like a special code that only you and your phone company know about, and it helps make sure that your phone works properly all the time.