Again thanks! I assume they take into account every month one has contributed to the Rentenversicherung in previous occupations (Zivildienst, work during ugrad etc.).
Thanks to the previous posters for your detailed answers. Related, are you forced to retire @ 67? and is there a minmum nuber of years you need to have worked to get a full pension? What I am getting at is, is there some age at which moving back is simply not an option any longer?You are forced to retire at 67 (at least for the moment), and your pension is a linear function of the number of years you have worked, with the full pension being achieved with 40 years of work experience. Work outside the German university system may be counted, but you need to double-check and possibly negotiate this.
However, if you are older than 40-50 (depending on the state) becoming "beamter" is no longer possible, and the conditions when being "angestellter" are generally not very attractive.