The perceived speech quality of a mobile phone essentially depends on the quality and the local conditions of the mobile network. A qualitatively poor mobile phone in an area with good coverage has a somewhat better sound than a very good quality mobile phone in an area where the quality of coverage is poor. Dead zones or high car speeds can result in a significant loss of quality. Furthermore, network quality is not a fixed condition. Modern UMTS networks, for example, are greatly affected by the traffic load or data throughput of subscribed telephones. It is for this reason that Müller-BBM frequently uses practical measured test runs, and conducts numerous test calls or data uploads and downloads to assess network quality.
We test network quality using our own test vehicle or a mobile measuring system in a suitcase or backpack, designed for use on trains or in open lots. By means of GPS positioning data, the measured signal parameters of mobile networks, such as the speech quality of test calls or the data throughput of an FTP connection, are entered directly into the map material and analysed statistically.