can you use iphone with a normal at&t plan?

Ya sure you can use iphone with AT&T sim only if it is unlocked one else if the iphone is locked to some other network provider then it wont accept your AT&T sim until you unlock it ...You can easily unlock the iphone through online providers like Mobile-Unlocker.com here they are rendering remote unlocking service to unlock all model iphone from network provider .You first check that whether the service is available for your country and network provider .If yes then pay for it and unlock the iphone then freely use it with any GSM sim ...