I'm traveling to SEAsia in a few months, Hong Kong, Vietnam, Cambodia and Thailand. I thought I'd bring back this thread with a question as to anyone's experiences with United Mobile, which used to be riiing.com.

I have a four-band GSM phone and I would like to get a world SIM card that will work in the US, as well as in the countries I mentioned. Any feedback on this SIM card? Or any others that might work for me?