## 2 Introduction  
Nowadays, mobile phones have become an indispensable part of society, impacting human lives in various aspects. Mobile phones and especially smartphones have revolutionised the methods of communication, connectivity and information access and have become the main devices used to access the internet. These phones enable real-time communication through calls and texts, effortlessly connecting people across the world. Through 4G data connections, mobile phones provide access to various messaging apps and a vast store of information at our fingertips. Additionally, mobile phones provide a lifeline during emergencies, allowing users to call for help, receive emergency alerts, and access critical information during natural disasters or other crises. Despite all the positive aspects brought about by this upward trend, from a technological point of view, mobile phones also introduce a series of elements that negatively impact society from a legal standpoint. The small dimensions, low battery consumption, ease of obtaining a SIM card with data and internet services, and extremely easy access to the internet make mobile phones a very dangerous device in areas where electronic devices are not allowed. One of the environments where phones are strictly prohibited due to security risks is a prison. Despite the regulations that completely prohibit mobile phones in prisons, there are prisoners who manage to gain access to such devices and subsequently access the internet. Over the years, several researchers have studied various security aspects related to mobile networks, as well as the possibility of increasing their resilience. In [1], the authors made a thorough survey regarding jamming attacks that can be performed on new-generation communication systems and their effect on LTE systems. Several jamming methods that were found to be disruptive for the LTE system were enumerated and, in the final part of this paper, several research directions for increasing the system resilience are highlighted. The authors of [2] also presented a comprehensive survey regarding the security attacks on an LTE system, which were classified based on the level they are performed on the OSI protocol stack. For each type of attack, the causes, implications and possibility of defence are presented. The authors also underlined the fact that there are still unsolved security breaches in the 5G air interface and offered several directions for future research. In another survey [3], the authors presented ample material regarding jamming attacks on different wireless networks, such as WLANs, cellular systems, Zigbee, Bluetooth, LoRa and RFID links, as well as anti-jamming strategies that have been identified. In [4], the authors presented a radio jammer for suppressing a detonation code transmitted using remote-controlled detonators; it was implemented with an optoelectronic device that produced replicas of a useful radio signal that degraded the quality of the transmitted signal. The device was simulated, designed and implemented as a prototype that validated the results. The authors of [4] presented a novel approach for implementing a jammer against wireless detonating devices by using optoelectronic equipment that generated replicas of the transmitted signal to destructively interfere with the correct one, and thus, reduce the signal-to-interference ratio, making the detonating code unrecognisable. The device was designed, developed and tested in MatLab, and then implemented as a prototype. In [5], the authors studied the vulnerability of LoRa radio links using single-tone, multi-tone and band-jamming strategies, with the results showing that this type of radio connection is robust to the type of jamming, with tone jamming being the most harmful one. The authors of [6] studied issues related to security aspects of low-power wide-area networks, including a review of the recently published research papers relevant to this domain, and identifying the critical attack vectors, as well as the most suitable protection and defence mechanisms.