A telephone calling interface is disclosed. An embodiment antenna circuit comprises a baseband signal processor, a pair of RF transmitters coupled to the baseband signal processor, a pair of PAs coupled to the RF transmitters, a 90\xb0180\xb0 hybrid coupler coupled to the RF transmitters, a pair of duplexers and two antennas coupled to the PAs. At least one of the walls has a multilevel surface with a plurality of sections in an overhanging relationship with each other and transitional curvilinear steps bridging adjacent one of the sections to impart a textured side surface resembling a natural rockface and allowing stripping of the dry cast products from an open bottom side of the compartment. A cleaning chemistry is injected into the processing chamber.