Will an unlocked Verizon iPhone work with AT&T?

I'm getting an unlocked iPhone from another carrier and plugging in my AT&T sim card to avoid having to pay for a data plan. All I need is Wi-Fi. If I get an unlocked verizon iPhone, will it work with att? I have heard mixed answers. Some say it is CMDA format and att only works with GSM phones. But, i heard all iPhones are gsm capable regardless of verizon carrier?

Only verizon iPhone 5, 5c, 5s come unlock and will work with Any GSM carrier including ATT. IPhone 4s verizon can only be used on verizon or GSM carrier outside the US. IPhone 4 verizon Does Not have a sim slot at all.

The Verizon iPhones since the iPhone 5 will work with US GSM carriers. However, AT&T's network will detect it and add a smart phone data plan to your account. Please understand this before you spend money on the phone. You will be paying for a data plan with AT&T.

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