The measuring data from the PIA geomagnetic observatory (Piran, Slovenia) to its server are transmitted via a mobile telephone network. From time to time, this communication is interrupted. For this reason, the wireless communication from the observatory to its server is the bottleneck of the entire system of collection, transmission, storage and processing of measuring data. However, wireless communication offers galvanic isolation of the observatory and protects it against the atmospheric electrical discharges. In the first ten effective rotations of the Sun in 2015 we registered the interruption of transmission and also collected the data about the conditions of the Sun and the conditions of the local weather in the Slovenian part of Istria. In the observed period, 91.6% of all measuring data were transmitted from the observatory to its server. The majority of interruptions of transmission were caused by the higher activity of the Sun. We shall use the results of analysis of all collected data to improve the reliability of the
transmission of measuring data from the observatory. They are useful also for the other users of mobile telephone network for transmission of measuring data in the real time.

Key words: measurements, mobile telephone network, real-time transmission, interruption