In a system for checking performance quality of mobile telephony networks, specific electronic devices (15, 15') are connected to digital data transmission lines (13, 13', 14, 14') between base stations controllers (11, 11') and base transmitting stations (12, 12') dedicated to peripheral areas, or cells, such devices being apt to acquisition of data transmitted onto said lines and to process said data for identification of specific network operating parameters and for correlation of said parameter between them. The above electronic devices are also connected to central processing units (30) where the above processed data are periodically transmitted to for later searching and processing according to design and network maintenance requirements, or any other requirement of users connected by means of remote terminals (31) to said central units.