Buy a Telcel prepaid SIM at any OXXO for 80 pesos and activate a data plan. Port your US number to Google Voice for $20 before you leave.
Which Carrier Should You Use in Baja?
Telcel. That is the short answer for anyone living on the peninsula. Telcel has the widest coverage in Mexico and the strongest signal in Baja specifically. It reaches Tijuana, Ensenada, La Paz, Los Cabos, and most of the Highway 1 corridor between them. AT&T Mexico works in the cities but drops out faster once you leave town. Movistar covers about 67 percent of the country with 4G and struggles in rural Baja.
Most of the peninsula between cities has no cell service from any carrier. The stretch between El Rosario and Guerrero Negro is mostly dead. So is the road between Loreto and La Paz in many spots. Telcel fills in more gaps than anyone else, which is why it matters.
How Do You Get a Mexican SIM Card?
Walk into any OXXO, 7-Eleven, or Telcel store. Ask for a “chip Telcel.” It costs 80 pesos, roughly $4 USD. The clerk will open the package, pop the SIM into your phone, and you are live on the network within minutes.
Your phone must be unlocked. If you bought it through a US carrier on a payment plan, it may still be locked. Check before you cross the border. AT&T, T-Mobile, and Verizon all unlock phones after they are paid off. Call your carrier and confirm.
Once the SIM is active, buy an “Amigo Sin Limite” plan. These are Telcel’s prepaid packages. The 200-peso plan (about $11 USD) gives you 3 GB of data for 30 days. It includes unlimited calls and texts to Mexico, the US, and Canada. It also includes unlimited WhatsApp and Facebook. The 300-peso plan bumps data to 4 GB. The 500-peso plan gives 6 GB. You recharge at any OXXO register, through the Mi Telcel app, or by texting “SL200” (or whatever amount) to 5050.
AT&T Mexico is the second option. Their SIM costs about 100 pesos. A 150-peso plan gives 4.6 GB for 20 days. Coverage is solid in Tijuana, Los Cabos, and La Paz but thinner than Telcel elsewhere on the peninsula.
What About the New Registration Law?
Mexico now requires every cell phone line to be registered with a government ID. The law took effect January 9, 2026. If you buy a new SIM after that date, the store registers it at the point of sale. Bring your passport. If you have temporary or permanent residency, bring your CURP number too.
If you already have a Mexican number, you must register it before June 30, 2026. Unregistered lines face suspension starting July 1. You can register in person at a Telcel, AT&T, or Movistar service center. You can also register online through your carrier’s portal. Telcel’s registration page is accessible through the Mi Telcel app.
Foreigners without residency register with a passport alone. Residents register with their CURP. The process takes a few minutes either way.
How Do You Keep Your US Number?
Port it to Google Voice before you leave the United States. This is the single most important step. Google Voice costs $20 for the port, and then it is free to use.
Here is how it works. Go to voice.google.com and sign up. Choose “port your existing number.” Pay the $20 fee. Google contacts your US carrier and transfers your number. The process takes one to three days. Your US carrier plan cancels automatically when the port completes.
Once ported, your US number lives inside the Google Voice app. Calls and texts to your old US number ring through the app. You answer them on your phone in Mexico over WiFi or your Telcel data connection. People calling from the US see your original number. They do not know you are in Baja.
You must be physically in the US or able to receive a verification call on your current number when you start the port. Do this before you move. Trying to port from Mexico is possible with a VPN and help from someone stateside, but it is harder and less reliable.
What Are the Limitations of Google Voice?
Some banks, apps, and services do not accept Google Voice numbers for two-factor authentication. They detect it as a VoIP number, not a carrier number. PayPal, some banks, and certain apps may reject it for SMS verification codes.
Before you port, update your two-factor authentication on every account that uses your phone number. Switch to an authenticator app like Google Authenticator or Authy. This way you do not depend on SMS codes arriving at a number that some services refuse to text.
Google Voice also requires a Google account. If you lose access to that account, you lose your US number. Enable two-factor authentication on your Google account itself using a hardware key or authenticator app. Do not create a single point of failure.
Can You Keep Your US Carrier Plan Instead?
You can, but it costs more and may not last. T-Mobile includes free international roaming in most plans. You get unlimited texts and data at reduced speeds (256 Kbps) in Mexico. Calls cost $0.25 per minute. But T-Mobile’s terms say roaming is for travel, not permanent relocation. If most of your usage happens in Mexico for months, they can restrict or cancel your service.
AT&T and Verizon charge for international roaming unless you add a travel pass. AT&T’s International Day Pass costs $12 per day. That adds up to $360 per month. Not practical for someone living in Baja full time.
The cheapest way to keep a US carrier number alive is the lowest available plan. Some carriers offer plans starting around $15 to $25 per month. You keep the number active and use it only when you cross back to San Diego or fly to the US. But $180 to $300 per year for a number you rarely use is expensive compared to the $20 Google Voice port.
What About Dual SIM and eSIM?
Most phones made after 2019 support either dual physical SIMs or one physical SIM plus an eSIM. This lets you run two numbers on one phone: your Mexican Telcel line and your US number.
If you port your US number to Google Voice, you only need one SIM slot for Telcel. Google Voice runs over data. But if you keep a US carrier plan, you can put the US SIM in one slot and a Mexican SIM in the other. Your phone handles both simultaneously.
Telcel sells eSIMs for tourists through telcel.com/travel-to-mexico. These work for short visits but are not ideal for residents. A physical Telcel SIM from OXXO is cheaper and easier to recharge locally.
Where Do You Buy and Recharge in Baja?
OXXO is everywhere. Tijuana alone has hundreds of locations. Ensenada, La Paz, and Los Cabos all have OXXO stores within walking distance of most neighborhoods. Walk in, tell the cashier “recarga Telcel, doscientos pesos” (or whatever amount), and give them your phone number. They print a receipt. Your plan activates instantly.
Telcel stores handle SIM replacements, plan changes, and account issues. In Tijuana, the main Telcel store is in Plaza Rio on Paseo de los Heroes. In La Paz, there is a Telcel store on Calle 5 de Febrero near the malecon. In Cabo San Lucas, the Telcel store is in Plaza Bonita on Boulevard Lazaro Cardenas. In Ensenada, the Telcel store is on Avenida Reforma near the Costco area.
The Mi Telcel app handles recharges, plan changes, and data monitoring from your phone. Download it before you need it.
What About WhatsApp?
WhatsApp is the default communication tool in Mexico. Businesses, landlords, doctors, mechanics, government offices, and your neighbors all use it. Your Mexican phone number becomes your WhatsApp number. You cannot function in Baja without it.
When you insert your Telcel SIM, WhatsApp will ask if you want to switch to your new Mexican number. Say yes. You keep your chat history and contacts. Anyone with your old US number can still find you if they have your new number saved.
If you want WhatsApp on your US number too, you can run WhatsApp Business on the same phone with a second number. But most expats just switch to their Mexican number and tell their US contacts the new one.
The Setup Checklist
Before you leave the US: unlock your phone and port your US number to Google Voice ($20). Switch all two-factor authentication to an authenticator app. Download the Google Voice app.
After you arrive in Baja: buy a Telcel SIM at OXXO (80 pesos). Activate an Amigo Sin Limite plan (200 to 500 pesos). Register the line with your passport. Switch WhatsApp to your new Mexican number. Download the Mi Telcel app for recharges.
Total cost for the transition: $20 USD for Google Voice plus 280 pesos (about $15 USD) for the SIM and first month of service. Under $40 USD, and you have both numbers working on one phone.
Regulations and government processes change. This article reflects information current as of March 2026. For advice specific to your situation, consult a licensed immigration consultant or contact the relevant government office directly.