We discuss how Mexican drug cartels developed sophisticated, independent cellular networks to evade surveillance from governments and rival organizations. These private networks utilized older 2G/3G low-frequency technologies, like OpenBTS software and specialized hardware, to minimize the need for numerous cell towers, especially in remote areas. A key innovation highlighted is their advanced encryption methods, which generated temporary keys based on local geographic and environmental conditions, making interception extremely difficult. The text further explains that this technology, initially implemented by groups like Las Zetas with the help of kidnapped engineers, is now becoming more accessible and affordable for companies and individuals seeking secure, private communication off the public grid.