See:
Fernweh war gestern: "Global Friends für o2 o" macht Schluss mit hohen Kosten für Handygespräche ins Ausland
This is the German version of the now discontinued o2UK/Jajah deal called "International friends and family" deal which was discussed here:
http://www.prepaidgsm.net/forum/euro...ing-calls.html. It is available for prepaid cards as well as contracts, and may be of benefit to some high volume callers.
Users can select 5 international numbers (2 can be mobiles) which are accessed via a short number. They are charged at 15c/min until you hit a 50 Euro price-cap. After this, all further calls during the month are free (both national and international to these 5 numbers).