I'm getting really confused by the different people marketing Travelsim. The Australian one doesn't even tell anyone what the validity period is. Only one says it has coverage in Vietnam (
http://www.travelsim.com/content/eng/41/) and it doesn't say what the validity period is either---surely basic essential information. Travelsimshop doesn't cover Vietnam but is way cheaper than the others and has a 24 month validity period.
Makes me more inclined to deal with the locals.
Cheers