We spent April in Vietnam and used Airalo for various e-sims. The first e-sim we purchased was valid for 10 days, so once that expired we purchased another from them. The same e-sim wasn't available so we got a 7 day'er. Once that expired, we purchased a regional e-sim (Asia) that lasted 10 days from them. The customer service was reasonably prompt (no longer than 20 mins at the worst to respond to us via chat). Note that you need to be on wifi in order to start using the e-sim. One thing, and this isn't Airalo's fault, but you follow the instructions on how to set it up and you have this niggling feeling that your Telstra (or Oz sim) is being used for data, when it's not. So I spent the first few days checking my Telstra account to make sure I wasn't bleeding roaming data. Another thing to note, its that each of the e-sims we purchased required slightly different setup instructions and settings. It worked fine for Googling and using maps and booking flights etc. We didn't use it for streaming or anything data intensive. Ended up going with Airalo because they're based in Singapore and I figured communication would be decent - which it was. They charge in USD. If you use my code GREG7286 we will both get a USD $3 credit.