While participating in a group call on a first wireless communication resource 114, senior members 104-107 of a communication group 108 can initiate a semi-private call. A central controller 110 allocates a second wireless communication resource 115 for the semi-private call. Furthermore, executive members...http://www.google.de/patents/US5473605?utm_source=gb-gplus-sharePatent US5473605 - Method for a communication unit to participate in multiple calls
