How easy (in terms of procedure time, accessibility and cost) is it to get a new SIM in Laos and Vietnam? I'm traveling to Laos by air and Vietnam by land. Will I be able to get a SIM at Laos airport? Are they compatible with most mobile phones? Or, should I take international roaming on my native SIM (which is of an Indian operator) I'm asking about the compatibility because of an experience in Nepal.