The present invention is a method and apparatus for selectively controlling the interconnectivity of two or more active telephone lines and/or one or more audio characteristics of each of the active telephone liens during a multi-line call. A bridge or a call connection control may be implemented to...http://www.google.co.uk/patents/US6453022?utm_source=gb-gplus-sharePatent US6453022 - Multi-line telephone with input/output mixing and audio control
