SipGate.de provides a free incoming German number with a number of restrictions.
If you don’t live in Germany or know someone who does, you probably won’t be able to get your own number. Due to German law, you have to live in Germany to get your own number. This may explain the lack of German incoming services. Skype offers a Germany income income number as well, but you have to pay a monthly fee to use it and also you are required to live in Germany.