you will have to call your provider and ask them to add "International" calling.
Then it will be a fee for each call received and called.
Then when you get home call and drop the International portion.
I do it each time I travel and it works very well.
Actually AT&T messed me up in June and I could not call out but could receive calls and text out. A friend called the service center and they fixed it so afterward that I was able to call out also.
But then again, possibly your provider has it on your phone already. It is worth a call to check it out.