Default [Q] Using Z2 internationally with T-Mobile USA

Hello Everyone,

I had a question about using my Z2 while in Europe for vacation. My mobile provided is T-Mobile USA. I have the international version of the Z2; model number D6503.

Basically, I want to know if the phone will automatically connect to mobile networks in Europe by itself or if I will have to change options on the phone such as the APN in order for me to get mobile service? The country in question is Bulgaria, and per T-Mobile's site they do have service there.

In the USA, the phone set itself up, all I had to do was select download internet and MMS settings and I was good to go. Will I have to do something similar like that while in another country or will the default T-Mobile APN suffice?

Thank you for your time and assistance!