Using an english iphone internationally? Consfused

I'm staying in the UK at the moment and in 2 weeks I will be living in France for a year.

I want to buy an iphone in the UK off ebay, but if I buy an iphone in England can I just put a French sim card in and use it in France?

Is there anyone who can explain what 'unlocked' means in regards to iphones? Will I need to buy an 'unlocked' one even if I put a new sim card in in France?

Yes, you should buy an 'unlocked' iphone if you're planing to use it with any sim card.
If it says 't-mobile, vodafone, at&t… ' etc (not sure what network operators are in uk), than it means it's locked to that operator and you won't be able to use your sim card in it.
So just go for unlocked one!

  • Will Sprint Unlock My iPhone if I'm Traveling Internationally? I'm going to Philippines with my friend in two months and I was wondering if Sprint would unlock our iPhones. If they will, would it be free? Cause I plan on using it in Philippines. We're just going to buy a sim card. When I was with T-Mobile, they unlocked my phone for China.
  • Why won't my iPhone 4S make or receive calls when traveling internationally? Celluar data is turned off because i don't want to get charged. My phone worked the first week I was in France. Now it doesn't work, still in France. My phone doesn't detect calls and when i dial numbers it doesn't ring
  • What is the best way to go about using my iPhone 6 internationally? I will be spending 5 months traveling through China, Vietnam, and Thailand and am wondering how I should use my iPhone 6. I've read about international SIM cards a little, but not sure how they work. IIm trying to find the cheapest way to have texting, calling, and data capability.
  • Using textplus internationally? I'm studying abroad in Spain and I downloaded the textplus app on my iphone. Can I use it to text my friends/family in the United States who don't have textplus without it charging them international rates?