Adding Vietnam Language Pack in basic phones?

Posted by Big_D
I have families in Vietnam that I'm planning on visiting soon.
I'd have several phones in my possession that I no longer use. I hope to give it to them to use but worry that I won't be able to change the default english language to vietnamese for them to use. most of the phones doesn't have the vietnamese language in the phones.
searching online I believe that there are region package that can be install in these phones for use in intended region and countries. I'd been to Vietnam and notice some of the phones they used are the same as mine.

Main question is even if I can't download and install those language pack myself, I can definitely take to a phone shop in Vietnam and have them do it at a price or is it impossible?

phones in question

- Samsung SGH-D600
- Samsung SGH-E600
- SAMSUNG T809
- SONY WALKMAN W580i

These phones seem to run on a Java OS, so I wonder if it's possible.

I'd notice that most of the smartphones I used, mainly Samsung and HTC doesn't even have Vietnam language available, only English, Spanish and French.

All Sony Xperia models I used, however, can change to the Vietnam or any other languages easily.

Posted by hihihans
I don't know about other brands but Sony Ericsson was easy to flash.
With Android I think you can just add a new language. Good luck.