Constantly increasing requirements on road safety lead to the development of new technologies and safety systems implemented in motor vehicles. Most of these systems help prevent accidents or reduce the severity of subsequent damage to persons and property occurred during an accident. However, these systems do not contribute to reduce the delay of the first aid ensured to injured persons. This function provides an emergency call system, which is capable of immediate detection of traffic accidents and ensures automatic transfer of information about the accident to the emergency call center. The information transfer is realized via GSM network, which may be disrupted by certain risk factors. The article presents the outcomes of the experiments in which these factors were evaluated.