Premise: How to call vietnam<br>Dial your country's exit code. When you want to call someone in vietnam and you're in a different country, the first thing you'll need to do is dial your country's exit code in order to get the call out of your country. These vary from country to country but many are 0-0 or 0-1-1.
Hypothesis: Calls to vietnam when you're in a different country use 0-0 or 0-1-1 followed by the local area code.