German Cellular Networks

Usually if you have one or the other - they will go over the local. I assume you are taking your tmobile from USA. It will just pick up the local network and you will pay the 1-2$/min roaming fee.

The GSM network coverages of T-mobile and E-plus are both pretty much nationwide. You might find a dead spot here or there, but that's a very local phenomenon in both networks.

The UMTS networks are less compehensive, i.e. there are sizeable rural areas which don't have coverage.
The T-mobile UMTS network is a little bit more complete though.

Emil,

To expand on Tom's post, it would help to know whether you're planning to use roaming with your home network or purchase a SIM card when you arrive in Germany?

If you're going to be roaming with either T-Mobile or AT&T, the geographic coverage of the German networks won't be a factor as your phone will select the strongest signal.

Cheers!

To clarify, I was looking at buying a prepaid SIM card that is repelnished with E-Plus airtime reloads.

Forget about E-Plus. Their coverage is horrible. Even in downtown Frankfurt there are huge spots without! Quality and coverage wise T-Mobile and Vodafone are both #1, followed by o2 and then finally E-Plus.

Many thanks for the information. I'm going with T-Mobil.