If unlocked you should have no problems, but if locked to orange or vodafone etc you need to get the code for example on SE's or nokias on most recent versions. In phill they will unlock the phone but we have found its not a full unlock, for example a vodafone payg we forgot to get unlocked in te uk so in alabang they unlock it but it was able to make calls but not text messages

Which means its almost usless to the avg phill.
The networks are the same its not like japan which uses a different type.
if its dual band, most are now or even better triband it will work.