or installing any OS you want without voiding the warranty? I mean when you buy a computer, no one cares if you install Windows or Linux. So why do smartphone manufacturers care?
It is a NAT, but created by an operator.
The operator does not give you a real IP address, but instead hides you behind his own NAT and gives you one private address.
All my close friends, so 9 people.
It's a good test for friendships too. If they can't bother to create an account on Matrix for you, do you think they will do something more in the future when you need them?