Silent Calls – Causes and Measurements

The quality of telephone services is very important from either operator or subscriber point of view. One of the negative phenomenon which affects quality of telephone services is lack of speech signal during a call. This situation occurs relatively frequently in mobile telephony, and is called silent call (SC). Lack of speech signal can occur only once or many times during the call, and degrade connection quality. In this paper, an analysis of this phenomenon is presented. The research base are the results of measurements mobile network one of operators in Trójmiasto a large urban area consisting of three cities: Gdańsk, Gdynia, and Sopot. To estimate impact of silent calls on speech quality, mean opinion score index was calculated using POLQA algorithm.