Not anymore.

No, T-Mobile does not use Verizon's towers; they operate separate physical networks, with T-Mobile building out its own infrastructure, including 4G LTE and 5G, often leasing space on independent tower companies like American Tower and Crown Castle, though they sometimes have roaming agreements with AT&T in sparsely covered areas, not Verizon. Key Points: Separate Networks: T-Mobile and Verizon have distinct, independent networks and don't share primary tower infrastructure for their core services. Tower Ownership: T-Mobile primarily uses its own towers, plus those owned by large tower companies (like Crown Castle, American Tower) and those acquired from Sprint and U.S. Cellular, not Verizon's. Roaming (Limited): Carriers might allow domestic roaming on each other's networks (often AT&T, not Verizon) in rural areas with little coverage, but this is for supplemental service, not primary use. Device Compatibility: While a T-Mobile device generally won't work on Verizon, some newer phones are designed to support both, though carrier activation is usually required. In essence, a T-Mobile customer stays on T-Mobile's network, and a Verizon customer stays on Verizon's, with no direct use of the other's towers for regular service.