We describe a system to optimize performance of a mobile phone network towards a performance goal. The system receives performance data comprising aggregated data for a plurality of calls and commissions measurement data comprising data logged for a plurality of mobile phones, and outputs data for changing a configuration of said network. The system includes a performance monitoring system; a measurement data request system, wherein measurement data is selectively commissioned in response said performance mismatch; a measurement data analysis system to analyze the commissioned measurement data to determine a probable cause of said mismatch, and to provide analysis data identifying the probable cause; and an action determination system to receive said analysis data and to output action data dependent on the analysis data, the action data identifying one or more configuration changes to be made to the mobile phone network to reduce the mismatch.