Mexico’s telecom regulator, the Comisión Reguladora de Telecomunicaciones (CRT), reports 92.3 million mobile lines already linked to their owner’s identity, 76.9% of the lines covered by the process. Suspensions of unregistered lines ending in 4 began on October 16, and the next deadline, for lines ending in 5, is October 31. For any company that sends SMS, each two-week cutoff means a block of customers who stop receiving messages overnight: OTPs that never arrive, payment reminders that expire and campaigns with falling delivery rates. Here are the figures, the remaining calendar and what to do before each date.
What happened with lines ending in 4
The deadline for lines ending in 4 expired on October 15. From Friday the 16th, carriers had 72 hours to apply a temporary suspension to numbers that had not completed the link. The suspension covers calls, SMS and data; the earthquake alert and free access to emergency numbers (911, 079, 088 and 089) remain active.
Three things worth keeping in mind:
- It is not a cancellation. The user keeps the number and the balance; once the registration is completed, service is restored immediately.
- The process is free and requires a valid official ID and the CURP. It can be done online through each carrier’s portal or at a service center, and the online registration does not consume balance or data.
- The same rule applies to lines ending in 0, 1, 2 and 3, which were suspended in earlier cutoffs and can be reactivated at any time with the same process.
How many lines are already registered
As of October 6, the mobile line registration run by the CRT counted 92.3 million linked numbers, 76.9% of the lines covered by the process. Put another way: roughly one in four lines had not completed the registration with five cutoffs still ahead. If part of your contact base falls in that group, you will notice it in your delivery reports long before any official announcement.
The remaining calendar
| Last digit of the line | Registration deadline | What it overlaps with in the retail calendar |
|---|---|---|
| 5 | October 31, 2026 | Start of pre-Buen Fin campaigns |
| 6 | November 15, 2026 | El Buen Fin (November 13-17) |
| 7 | November 30, 2026 | Month-end and year-end bonus (aguinaldo) notices |
| 8 | December 15, 2026 | Holiday shopping and year-end payments |
| 9 | December 31, 2026 | Year-end close and the January slump |
This is no small detail: the five remaining cutoffs fall in the highest-volume messaging season of the year. The one for lines ending in 6 overlaps with El Buen Fin, and the ones for 8 and 9 with holiday shopping, the aguinaldo and year-end collection notices.
What it means for your SMS campaigns and OTPs
A suspended line does not receive SMS. On your platform that shows up as delivery reports with statuses such as UNDELIV or EXPIRED concentrated on numbers ending in the digit of the latest cutoff. In an OTP authentication flow the effect is immediate: the customer tries to log in, the code never arrives and the session is left halfway. In collections and reminders, the message is lost right when the customer’s attention is hardest to win back.
- Segment by last digit. Your contact base already has the data: filter the numbers ending in 5 and send them a reminder before October 31. Repeat with 6 before November 15, and so on through 9.
- Read delivery reports by last digit. If UNDELIV results for one digit spike after a cutoff, it is not a routing or content problem: it is the suspension. DLR webhooks let you spot it the same day.
- Have a fallback for the OTP. When the SMS cannot be delivered, a voice call with the code or an alternate channel keeps the user from being locked out. If your flow has no second attempt over another channel, now is a good time to add one.
- Do not retry blindly. Resending an OTP ten times to a suspended line does not deliver it and does consume messages. Flag the number as temporarily unreachable and try again when the delivery report changes.
Sample messages to warn your customers
- “[Company]: your line ends in 5. If you have not registered it with your CURP yet, do it before October 31 to keep receiving our notices and security codes.”
- “[Company]: starting November 15, unregistered lines ending in 6 will be suspended. Link your number with your carrier and avoid losing service during El Buen Fin.”
- “[Company]: didn’t get your verification code? Check that your line is registered with your carrier or request the code by phone call from the app.”
For the full process, the requirements and how the impact looks in delivery reports, see our guide on Mexico’s CURP phone registration and your SMS campaigns. And if you need to check how your traffic is being delivered over these weeks, request a demo and we will go through it with your own reports.
Sources
- “Inicia suspensión de líneas telefónicas con terminación 4 por falta de registro: esto es lo que debes saber”, El Informador, October 16, 2026. Read (in Spanish)
- “Avanza registro de líneas celulares en México con 92.3 millones”, El Momento, October 22, 2026, with data from the Comisión Reguladora de Telecomunicaciones. Read (in Spanish)
- Official registration portal: registratulinea.crt.gob.mx, Comisión Reguladora de Telecomunicaciones.
