My friend is coming to visit me for a month and I am planning to buy a Cingular prepaid sim card off ebay for her. Can I just buy a sim card, simply insert it in the cell phone, and begin using it? or do I need to registered with the company or join any plan?
Your Friend Phone needs to be an Unlocked Phone to use Cingular Sim card or any gsm network sim card...It's locked phone means you can't use it...You can unlock the Mobile phone using the unlock code at here Simpleunlocking.com and get the free Unlocking instructions at here Mobileunlockguide.com and unlock it step by step...Then use your Cingular sim with her Phone.
Note: You need to Unlock any phone to use other GSM sim cards....