What are the rules for using 3g overseas?

I'm going overseas for several months and I'm planning on using my IPhone while there just for social media and blogging. If i leave it on airplane mode, will i still have 3g to use to post pictures and connect to facebook even when not connected to Wi-Fi? I'll hardly ever be somewhere with internet unless I'm at an internet cafe, so I'm hoping to be able to post things easily without having to connect, so what are the rules about being international and not being connected to Wi-Fi?

No it want work… I have a 4g and it doesn't work… Unless I connect to Wi-Fi… But it depends on how far out you will be… I work deep offshore… Maybe I'm reading your question wrong… If you are talking about on land overseas I couldn't tell you… But I have a 35 dollar phone from the dollar store called a trackphone that work anywhere… And I paid 400 for my 4g… Dam shame.