AT&T SIM card is needed or if jailbroken/unlocked you can use T-MOBILE
Either apple or at&t because you need a special sim card
the iphone has a sim card which slots in the top of the iphone. to get the sim card tray out you have to use a pin or the special tool it came with to open it.
Yes the iphone 4 uses whats called a micro sim card it is smaller then the regular sim card out there. At www. phonetraderonline.com they can custom cut your existing sim card or provide you with a micro sim for your carrier.
Of course, the iPhone 3G and/or the original iPhone will take any normal sim card; the 3G iPhone will take the 3G sim as well.
The iphone 4 comes with a micro sim. Your normal sim will not work with it. My AT&T dealer says he can transfer data directly from your sim/old phone to your new iphone 4.
In the top of the iphone, next to the headphone socket. You will need to use a paperclip or similar to open the SIM slot.
Iphone uses sim cards to track the user and gets all hidden information from them
all iphones have a sim slot but on the original iphone the customer cannot easily access it whereas the 3G iphone has the sim card and a sim card ejector tool How can I access my verizon iphone 4 sim card slot that doesn't have a sim tray
Then just get an iPod touch ..
In some situations, the status bar on your iPhone might display No SIM, even though your iPhone has a SIM card.
No
No sim cards are only for numbers