T-Mobile USA

T-Mobile USA includes Vietnam roaming as standard for US-based customers, with no separate eSIM needed if you're already a T-Mobile subscriber. The carrier's International Day Pass lets you extend your home plan's data, calls, and texts to Vietnam without surprises. For non-T-Mobile users or those needing multiple countries, T-Mobile's 1-to-30-day International Passes cover 200+ destinations.

This option is ideal for US travelers who want to avoid the hassle of switching providers mid-trip. Built-in roaming means you keep your home number and don't juggle multiple eSIMs, which simplifies staying in touch with contacts at home. The Day Pass model lets you control costs, activate it only when you need data, then pause it during flights or at your hotel to stay on WiFi. Compared to dedicated travel eSIM companies, T-Mobile's advantage is simplicity and the ability to walk into a US store for support, though it's generally pricier than regional carriers.