If I buy an unlocked iPhone will I be able to use it with Metro PCS?

You are absolutely wrong. You have no idea what you are talking about. The only CDMA iPhones are for Sprint and Verizon. Neither one is portable to another network. AT&T is a GSM carrier. Unlocked iPhones will NOT work on ANY CDMA network. The CDMA side of unlocked iPhones is completely disabled.

I don't know whether you can use an iPhone 4 or 4s with metro pcs but if you can't it's not because of the CDMA network. It is true that metro is CDMA but the iPhone 4 was release in 2 versions one for AT&T which is gsm and one for verizon which is CDMA, just like metro. The iPhone 4s is a dual network phone and supports both gsm and CDMA.

metroPCS is not a supported carrier. While you may get service, it's likely that many of the features of the iphone such as Visual Voicemail, FaceTime, MMS, and 3G data speeds may not work.

MetroPCS is a CDMA carrier. You can not use an iPhone on their network at all.

good to know that, Kilted. Thanks.