Hello, I will be studying abroad for four months in the UK starting in January. What do I need to use in order to use a phone abroad? I was originally planning on only taking my phone to use on WiFi, but our program mandates we have a minimal amount of minutes available on phones for emergencies. Worst case, I buy a cheap phone in Europe for emergencies, but I'd rather not carry around something extra if I can get my iPhone to work. I am completely lost when it comes to understanding SIM cards/how to use/how to unlock. I have an iPhone 4S and use Verizon. Any help or tips would be extremely helpful. Thank you!