I'm living in Vietnam, where we have to unlock device before using Bold with local carriers. Bold 9000 World version are always much more expensive than locked ones, but after being unlocked, they will be the same, is it? How can I know if it is World one or an unlocked one?

Wirelessly posted (hope is everything!)

All bolds are pretty much the same they are all manufactured as gsm devices. They are all quad band which means they are world phones.

Unlocked phones generally carry a higher price but you can buy an unlocked phone and get it unlocked by www.horizonwirelessonline.com very inexpensively

Some Trader here label their Bold as "Free Sim" or "world version", then charge us a higher price than "unlocked" Bold. My question is how to know they sell a real free sim? I guess, it all unlocked!

I don't understand what you're saying. "Unlocked" means you can use any SIM. "World Phone" means it's compatible with all 4 GSM bands. All Bolds can be unlocked, and all Bolds have "World" access.