Cell Phone Service Provider in Vietnam

Ya, as an expat who formerly lived in Vietnam I would say prepaid is the way to go. Make sure you have an unlocked phone, otherwise you can purchase one for cheap when you get there. SIM cards are available at any 7-11 type shop - I would recommend either Viettel or Mobiphone. I would also recommend having your family phone you if you're tyring to keep in touch internationally - this is at no charge to you, whereas if you make the call the cost is high and will chow your airtime in notime.  Skype or any other VoIP service is a better option for maintaining these long-distance relationships - most Internet Cafes have headsets you can borrow - though then you'll have to deal with the fact that your conversation won't be private.