Mexican mobile phone numbers ending in the digit 1 must be registered with the federal Clave Única de Registro de Población (CURP) system by August 31, 2026. ^[1] The Comisión Reguladora de Telecomunicaciones (CRT) in Mexico initiated the suspension of mobile phone lines ending in 1 on September 1, 2026, to link each number with the identity of its holder for telecommunications control. ^[2] Telecom companies including Telcel, AT&T, and Movistar are authorized to suspend services for unregistered lines, with a grace period of up to 72 hours after the August 31, 2026 deadline. ^[3] Unregistered lines will be disabled for making or receiving calls, sending text messages, and using mobile data. ^[4] To reactivate communication, affected clients must visit service centers or use the digital platforms of each company to present valid official identification and their Clave Única de Registro de Población (CURP). ^[5] Users of Telcel, AT&T, Movistar, and other companies without mandatory registration who did not complete the verification process before August 31, 2026, will experience an interruption of their connectivity. ^[6] The federal registration program continues in phases based on the last digit of the phone number, with subsequent deadlines set for September 15, September 30, October 15, October 31, November 15, November 30, December 15, and December 31, 2026. ^[7]