Correct APN to use data roaming in EU?

My provider is Fonic, which uses the APN pinternet.interkom.net in Germany, no username or password.

I can't get my phone to connect data in any non-German European network, though. The solution seems to be to change the APN, but will I still use my data plan if I set up the APN of, say, movistar in Spain, even though the plan is by Fonic? The Fonic website has so far not disclosed any interesting information on the subject, at least not to me...