Yes, there is technology that can block cell phone signals, and such devices are often called cell phone signal blockers or signal jammers. They interfere with the communication between the phone and the base station by emitting radio waves at the same frequency as the mobile phone's communication, thereby blocking calls, text messages and data connections. However, the use of this technology is strictly regulated and legally restricted in many countries and regions, because it not only blocks the communication of the specific target, but may also affect the communication of others around. Therefore, the unauthorized use of these devices by non-law enforcement and security agencies is generally illegal. If you are concerned about safety issues or kidnapping, it is recommended to contact local law enforcement for help and advice.