Can iPhone 3GS bought in japan use prepaid sim card in the Philippines?
Yes, and unlocking it allows you to use other service providers.
Would iPhone 4S bought from US work with Philippines sim card?
Mine's doing the same thing!
You had a iPhone came from japan is it possible to get the warranty here in the Philippines?
It was created for mankind to have instad of crap
Does an iPhone bought 4 in the Philippines work in Qatar?
You bought iPhone 3G in Japan Can you use it in Bangladesh?
Probably not, because I don't think there are any carriers that the iPhone supports in Bangladesh.