An automated system that assesses the quality of service provided by a cellular radiotelephone system. The system uses apparatus located at a mobile station that remotely controls apparatus located at a fixed station. A cellular radiotelephone call is placed from the mobile station which is received...http://www.google.de/patents/US5644623?utm_source=gb-gplus-sharePatent US5644623 - Automated quality assessment system for cellular networks by using DTMF signals
