Upvote:5
You will absolutely be able to use your phone and you should have some decent data coverage as well; but you may run into issues where LTE (the high speed network) is not available on your device.
In Europe, the two predominant frequencies are 900/1800 this is for voice and text.
For data, each operator offers data service on different bands. Wikipedia has a page that lists LTE frequencies on major operators in Europe.
Your phone runs on the 1800 (band 3) and 900 (band 8); LTE on 850 (band 5) and 1900 (band 2).
This covers the large majority of operators.
Just make sure your device is not locked to AT&T (also called "sim locked"). If it is locked, you can call AT&T and request them to unlock your phone. There is usually a fee for this service.
Or can simply buy the phone "off contract" (unlocked).