Interface for connecting up to 8 additional call buttons to the built-in door intercom VT200TE8. Call button extension: Up to a total of 32 call buttons can be operated in the system. 8 cable connections for normally open contacts (NO). Loop-through connection via ribbon cable to the interface of the door intercom or to other interfaces. Power supply via the door intercom. Dimensions: 47 x 47 x 17mm.