The telephone signal was masked as if there was no service because it could only receive one of these frequencies. Less complex signal shielding devices can only block a set of frequencies, while complex GSM jammers can block multiple network types at the same time to turn off dual-mode or triple-mode phones. These phones automatically switch between different network types to Find the open signal. Some high-end gsm signal jamming devices will block all frequencies at the same time, while other high-end devices can be tuned to certain frequencies.
Some drivers have also equipped their vehicles with GPS jammers so that police or gendarmerie will not find them when speed limits are exceeded. This is prohibited by law and can lead to criminal prosecution and fines if checked. GPS signal jammers are also popular among thieves and therefore interfere with the frequency of remote shutdowns. You thought you closed the door, but didn't close it. The thief does not have to enter the vehicle until you turn around.
GSM frequency jammer is not a device suitable for your hand, it does not take up much space. However, it is a technical tool. It is not expensive, but it is not commercially available. The Internet and the black market are major suppliers of frequency jammers.