Can You Use your iPhone Oversize and Will there be Service?

Ok, My mum has an Samsung (Bought in Australia) and the Last time she went to Srilanka, Indian and All that, it had service from their Network and could Call! I just want to know, if my iPhone (Bought in Australia) will have service and to be able call in Srilanka? If not, what can i do?

It depends with your telco provider. Most often if you are allowed to call someone from a country outside your current residence, there will be charges.

If you have internet connection, you can try using Viber.