Does my U.S. carrier plan (AT&T, T-Mobile, Verizon) include free roaming in Guam, or is a DataESIM recommended?

Despite Guam being a U.S. Territory, most major U.S. carriers like AT&T, T-Mobile, and Verizon do not automatically include it in their standard domestic plans. Relying on your existing plan can lead to exorbitant pay-per-use roaming charges (often exceeding $3/MB) or severe data throttling to unusable 2G/3G speeds. For heavy data users, remote workers, and digital nomads, a dedicated DataESIM for Guam is highly recommended to ensure consistent, high-speed 4G/LTE (and often 5G) connectivity without unexpected costs or performance degradation.