No, you're missing my point. It's not that SIM cards are a different size, shape, or that the GSM frequency is different (which is true, but can be overcome by the fact you have a triband phone).
The issue in the US is that not all networks use GSM. Period. It's like trying to put Mac software in a PC
, without an emulator. This idea is incomprehensible to Europeans, where all the cellular systems are (ideally) compatible. If only it were like that here.
HOWEVER, here in the US, cellphone systems are physically different. Because of differences in network technology between different systems (think of it like this: it's like a French person, that only speaks French, trying to commute with a person who only speaks Chinese), there is fragmentation in the US market where it does not exist in the (much better planned) European cellular system.
Virgin Mobile USA is similar to Virgin Mobile UK only in NAME. They are completely different technologies, using completely different systems, in completely different ways.
Again, there ARE GSM companies in the US that are compatible with the European (and indeed, Global) system - T-Mobile, AT
&T GSM and Cingular GSM. However, most other networks are NOT the same.
Because the technology is not the same, the use of SIM cards does not exist, either, in anything other than GSM (and iDEN) networks. iDEN is a completely different technology, and offered only by a company called Nextel, so discount that idea right off the bat.
The ultimate point (and I do have one, I promise) is that you can get a lot of different types of pre-paid cellphones here. But don't try and be "clever" and use your own phone. Just take what they give you.
Otherwise, go with AT
&T Wireless' "GO PHONE" and that is GSM and thus, will solve all your problems.
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