A:AnswerYes, an unlocked iPhone 8 Plus will work on T-Mobile. It will work equally well on Verizon and AT&T as well as any boutique cellular phone company in the USA (like Mint Mobile, Boost Mobile, Cricket, Straight Talk, etc.) since none of those smaller companies own cell towers but instead lease access to the tower networks owned by one of the big 3 (meaning Verizon, AT&T and T-Mobile [which merged with Sprint in 2020]).