What companies uses SIM cards?

I am about to purchase an UNLOCKED GSM and trying to figure out the companies that will have a SIM card included.

What companies uses SIM cards?
Are you American? If you're looking for a national carrier only AT%26amp;T and T-Mobile use GSM.





Once you get your unlocked phone, just go to a company store and ask them you want to set up a new line with your own phone, and you just need a new sim card. the card will be $25, plus the cost of activation, etc.
Reply:fido and rogers-canada


t-mobile and at%26amp;t-usa
Reply:T-Mobile and AT%26amp;T. You have to be careful, since the frequencies for both companies is not the same. So, even some tri-band phones may not work on both networks. You could play safe and buy a quad-band phone. Or, before purchasing the phone, make sure that the frequencies of that phone are compatible with both providers. By the way, if you know which network you're going to sign up with, they will give you a choice from some very good phones (2-year contract) free of cost.
Reply:At%26amp;t
Reply:AT%26amp;T, Tmobile, %26amp; Sprint





NOT Verizon %26amp; Metro PCS
Reply:most of the time t-mobil does and losts of prepaid phones have them.