Is it illegal to switch SIM cards between phones without advising the wireless phone company?

I have friends that do this all the time. I was just wondering if that was illegal or if they have to pay a fine every time they do it. Does the SIM card track your records and send it to the wireless phone company? It seems wierd!?

Is it illegal to switch SIM cards between phones without advising the wireless phone company?
It's perfectly legal cos they bill you for the cellular service and not the technology used to deliver the service. Cingular, T-Mobile, US Cellular support SIM technology, but they don't own the phone companies (e.g. Nokia, Siemens, etc).





The only thing they try and do to keep you on their network is to make some of the phones you get with their plans network "locked". For example, you get a free/discounted phone when you take out a plan with T-Mobile, there's a high probability that the phone will be "locked" to the T-Mobile network. U can change the SIMs in these phones too, but will only be able to use the cellular service if the SIM is to be use via their network and not a competitor. Get it?
Reply:It is not illegal to change your sim cards, and there is no fine if you do this with Cingular.





They can probably track, but I'm npt 100 percent certain.