Originally Posted by ColsTiger
Nobody on here really knows whether the SIM will work in other phones besides the iPhone. That's something we'll have to wait until Friday to find out.
I'm only going by the fact that the source stated in the article that you could actually put another GSM phone's SIM into the iPhone, but ONLY the phone features would work, other features such as DATA, VOICEMAIL, and even IPOD would cease to function. If that is the case, then the reverse should be true also, using an iPhone SIM in a regular old GSM phone.
This could be due to a number of things, it could be something actually in the iPhone SIM that "unlocks" the iPhone's features, or it could be due to the fact that in order for a GSM sim to fully function in an iPhone it would have to be provisioned into AT&T's iPlan feature set to function properly.
There has been a lot of rumor that there is SOMETHING different about the iPhone sim itself. These rumors range from the SIM actually being completely different in terms of the size, to the SIM just being different. These rumors are most likely based in fact on some level, but you know how that works. Sorta like whisper down the line.
Now, here's my take on the situation. The iPhone is a GSM phone, most likely the SIM will be the same size, and also adhere to the basic GSM SIM feature set.
The word on the street is that "When you get your iPhone you will NEED to use the included iPhone SIM... If you have an existing AT&T account, you will not be able to use your existing SIM into the iPhone and have it work properly."
This does not however mean that all GSM compatibility has been completely thrown out the window, as some have come to assume.