Can I buy an iPhone and use it in another country?

If you buy an iPhone in one country / region to use in another:

• The warranty might not be valid in the country in which you intend to use it.
• The phone's cellular radio coverage might not be tailored for the country in which you intend to use it

I don't have enough information to really answer your question – just to raise more questions. Maybe someone else will have a better idea.

There is no such thing as an International iPhone. iPhones are region specific because different countries use different cellular frequencies.

Buy your phone here -

Apple launches Apple Store online in Vietnam - Apple

Why not? All other cellular phones work except for iPhone. I’ve got me a cheap Samsung A15 and I can use it everywhere but my expensive iPhone will not do the basic thing which is to connect to a carriers network.

Do I have to buy a new iPhone each time I travel?

Are you asking where to buy an iPhone to use in VN (Vietnam?!?)?

It’s ALWAYS best to purchase an iPhone in the country of residence and/or primary use.

There is no “international iPhone”.

You can buy an iPhone in Canada, the problems is warranty and repairs in case you need it they will not work in VN, instead Apple opened a Store there maybe it’s better to do so.

Are the UK and Australia on the same frequency? I understand UK is GSM, but cannot confirm what Aus is.

I’m aware on the warranty issue, and that the phone needs to be unlocked.