Purchased an o2 SIM card in Germany and was able to use it, however, the US N5 is different from the rest of the world so I didn't have LTE. I did have the H symbol, so faster than 3G but not quite LTE. After some research I found out European LTE cannot be picked up with a US N5. Also, I had to manually select my carrier, it didn't automatically register when I put in my o2 SIM card. There is a lot of talk on the internet about purchasing a SIM card from LIDL or ALDI but they changed their options as of a few months ago so you can only get internet if you purchase the monthly plan. No prepaid internet anymore. O2 just wanted to see my passport and they set everything up. I got 2 SIM cards from them for 10 euros. The only downside is that Android OS used an insane amount of data. Like 50+ MB / day at times. I even had background data off. Oh and several people commented on the good picture quality. Even IPhone users.