Same solution I would suggest here: get a prepaid SIM card from one of the local providers (let me check my notes...)
Either get a tri-band phone here, and use it with the SIM card you buy over there. Or just buy a phone on ebay Germany and have it sent to your Landstuhl address.
Incoming calls on European cellphones are free; the calling party pays. You're "area code" will be different from the local area code.
SIM card: Subscriber Identification Module, a little chip that can be put into any compatible GSM phone.
GSM: the standard for cellphones outside the US. US GSM phones however are not compatible with European ones, due to them working on different frequencies. That's where you need a tri-band phone if you want to use the same phone all over the world.
A pair of cheap throwaway phones like the Nokia 3310 (for Europe) and the Nokia 3390 (for the US) will do just as fine.