One possibility which is working in all european countries would be to buy an airBalticcard | About airBalticcard Mobile
and use SparRuf – mit dem Handy billig ins Ausland telefonieren
for forwarding incoming calls.
You pay 19/min for incoming calls, settled from your sparruf account, people who call you pay their national landline rate.
Outgoing calls are ca. 45ct/min with the airbalticcard.
The airbalticcard is roamingfree in all european countries.