Is roaming free in Cambodia with my Thai or Vietnamese SIM card?

It's important to be aware that Cambodia is generally not included in regional roaming agreements that might exist between other Southeast Asian countries. Therefore, using a SIM card from Thailand or Vietnam in Cambodia will almost certainly incur significant international roaming charges, which can be surprisingly high. To avoid these costly fees and ensure seamless, affordable connectivity while exploring Siem Reap, Phnom Penh, or the temples of Angkor Wat, we highly recommend purchasing a dedicated EastESIM Cambodia plan. It offers reliable service with local partners like Smart Axiata or Cellcard.