rer did not necessarily indicate the quality of the service. This was due to the error-correction scheme built into the coding schemes. Since voice was the first service to be offered in mobile networks, voice call quality has received a lot of attention. In seeking a measure of quality that could measure the voice quality, as perceived by the human ear, a measure was developed called the 'mean opinion score' or MOS. In its 'pure' form this consists of a panel of humans who are asked to score the voice quality of a sample recorded from a mobile phone. Since these are subjective tests, the results are dependent on the types of people listening and even on the language used for the testing. This kind of testing is very long as well as expensive to do. The MOS was then automated and measurement tools are available for measurement, which try to mimic the performance of the human ear. Typically MOS has a score range of 1 to 5. The result of 5 is the best and 1 is the worst. Most 2G systems with the EFR (Enhanced Full Rate) codec can give a MOS score of between 3 to 4, depending on network conditions. MOS testing can be done only with drive test equipment. Packet Call Quality The packet call is characterised by two measurements: the latency and the throughput. Throughput can be described as the size of the data pipe available to the user, and latency can be described as the speed at which the data flow can start. Throughput Throughput is a measure of the size of data that can be transferred to and from the mobile user. Throughput is typically measured by doing an FTP (file transfer protocol) transfer of a file over the network and then working out the time taken. Typical file size for testing used is 1 Mb. This large file size is used SO that the effects of cell changes are averaged out. Throughput depends heavily on the capability of the mobile to use multiple time slots in 2G networks and using different sized bearers in 3G. Hence throughput is specified and measured per time slot in 2G and 2.5G networks and per bear