In the CDMA environment, a local call is directly made between two mobile stations (MS) without the involvement of a base station. The local direct calls do not interfere with any existing communication lines, and the implementation on the CDMA based units includes Master MS units and Slave MS units...http://www.google.de/patents/US6650629?utm_source=gb-gplus-sharePatent US6650629 - Method and system for terminal communication
