Here's the story of one tech blogger who got his iPhone unlocked so he could purchase short term data plans while traveling internationally. He visited Portugal and the UK.
http://sixcolors.com/post/2015/05/simply-irresistible-an-unlocked-phone-is-a-travelers-best-friend/
http://sixcolors.com/post/2015/05/simply-irresistible-an-unlocked-phone-is-a-travelers-best-friend/