JAZZ AND BREAKFAST - a series of events hosted by Deutsche Oper Berlin and the Deutsche Oper Restaurant. Every first Sunday in the month the restaurant at Bismarckstraße 35 presens breakfasters with a charming blend of acoustic and gastronomic delights - a doubtless unique event in the city. Working in close collaboration with Deutsche Oper Big Band members Sebastian „Sese” Krol and Rüdiger„Rübe” Ruppert (also regular members of the Deutsche Oper Berlin Orchestra), Martin Hattenbach of the rdo will be serving up five concerts in this series, entitled JAZZ & BREAKFAST. Source
We don't know about any regular jam sessions at Deutsche Oper Berlin.