T-Mobile Samsung Galaxy S7 Edge incompatible with Verizon?

Anyone with smartphone expertise know the answer to why a Samsung Galaxy S7 Edge I want to buy off a friend is incompatible with Verizon? I know T-Mobile uses GSM while Verizon comes with CDMA, but all S7 Edge's should have both types of hardware. Is this phone actually incompatible or this Verizon being ***** and trying to make me buy a phone from them? They told me the phone doesn't have CDMA hardware, but I'm having a hard time believing that.

Also, the phone was obtained through the "Buy 1 phone, get 1 free" type of promotion. Are promotional phones from T-Mobile GSM-Only?

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