Before you start

An unlocked, band-compatible handset — ideally dual-SIM or eSIM-capable
Passport, or resident card once issued
A CURP — residents get one automatically, and non-residents can pull a temporary one from RENAPO
A Mexican payment method for postpaid plans

Step-by-step

1
Buy prepaid on arrival
Telcel Amigo has the broadest coverage in the country and is the safe default if you will drive to Ensenada, the Valle de Guadalupe or Mexicali. Bait, on the Altan network, and weex are cheaper but thinner outside the built-up area. SIMs are sold at OXXO, Walmart, carrier stores and the airport.
In personWho: YouUnder 30 minutesMXN 50–150 for the SIM
2
Register the line to your CURP and ID
Link the number to your CURP and a passport, INE or resident card through the carrier's portal or app. It is free, takes minutes, and is now the difference between a working line and a dead one. One person may hold up to ten lines under a single CURP. Postpaid contracts were registered when you signed them; it is prepaid that needs doing.
OnlineWho: Every prepaid line holderSame dayFree
3
Turn off automatic network selection near the line, or pay for it
US carrier signal reaches well into Tijuana, and a handset left on automatic will happily register on a US network while you are sitting in your own kitchen in Playas or Zona Norte. On a Mexican prepaid plan that is international roaming at international roaming prices. Set the network selection to manual and lock it to your Mexican carrier, or check that your plan explicitly includes US roaming — several Mexican plans do, and that is the neater answer.
Mobile appWho: Everyone, especially near the borderFive minutes
4
Consider a plan that covers both countries, or run two lines
Telcel and its competitors sell plans that include US and Canada usage, and US carriers sell plans that include Mexico. Which is cheaper depends entirely on where your data actually gets used. Commuters commonly run two lines in a dual-SIM handset — a Mexican number for local life and banking codes, and a US number for the employer, the bank and anything that will not send an SMS internationally.
OnlineWho: Cross-border commuters≈MXN 200–600 a month for a Mexican postpaid plan
5
Switch to postpaid once you have a bank account
Postpaid plans cost less per gigabyte but require a credit check, a Mexican address and usually a local card or direct debit. Most newcomers qualify after a few months of a Mexican salary. Number portability lets you keep your number; never cancel the old plan before the transfer completes.
OnlineWho: You
6
Order fibre and check what the hills do to fixed wireless
Telmex, Totalplay and Izzi cover most of Tijuana and fibre is cheap by international standards, but the city is built over steep canyons and ridges and coverage is genuinely uneven street to street rather than colonia to colonia. If you work from home, confirm the service at the exact address before signing a lease, and treat any fixed-wireless offer with suspicion until you have seen it work in that room.
OnlineWho: YouOne to three weeks including an engineer visit

Documents you’ll need

Passport or resident card
CURP, definitive or temporary
Mexican bank card or account for postpaid billing
Proof of address for fixed-line installation

Things most newcomers don’t know

Your phone can roam onto a US network without you leaving your flat.

Radio does not stop at the fence. In Playas, parts of Centro and anywhere on the northern ridges, US carrier signal is often stronger than the Mexican one, and a handset set to automatic network selection will take it. People discover this on a bill. Locking network selection to your Mexican carrier, or buying a plan that explicitly includes the United States, is a five-minute fix that nobody warns newcomers about because locals learned it years ago.

Source: community-reported

The registry that came back is CURP-based, not biometric — and it will suspend your line.

The Supreme Court struck down PANAUT, which would have collected fingerprints and iris scans, and many arrivals still believe Mexican prepaid is anonymous. Linking a line to a CURP became compulsory on 9 January 2026, and unregistered prepaid numbers are being suspended on a rolling calendar running from 15 August to 31 December 2026 by the last digit. No biometrics are taken, but a suspended SIM stops receiving your bank codes.

Source: CRT — registro de líneas móviles

You do not need residency to register a line — a temporary CURP is enough.

People on a tourist entry assume the registration rule locks them out of a Mexican number entirely. RENAPO issues a temporary CURP to foreigners against a passport, free and online, and that satisfies the requirement. In a border city where people often arrive before their residency does, this is the difference between a working Mexican number and months of roaming.

Source: RENAPO / gob.mx

A US bank or employer that will not text an international number is a real, common problem here.

Plenty of US institutions refuse to send verification codes to a +52 number, and plenty of Mexican ones refuse to send to a +1. Cross-border households solve it with two lines in one handset rather than by arguing with either institution. Decide which number each account gets before you open the accounts, because changing it later is a support call per account.

Source: community-reported

Common mistakes to avoid

Leaving network selection on automatic and roaming onto a US carrier from your own home.
Never registering the line to a CURP and losing the number and your two-factor codes.
Assuming a tourist cannot register a line — a free temporary CURP solves it.
Signing a lease on a canyon-side address without confirming fixed internet at that exact house.
Putting every account's verification codes on one number in one country.

Some of this may be out of date. Spotted something inaccurate? Help us keep it right for the next newcomer.