Many of our favorite phones support more than one SIM at a time, giving you two phone networks on your phone. Some carriers lock their phones so that you can only use their SIMs for a limited amount of time, but can be unlocked after a few months. If you bought your phone unlocked or have had it long enough that it’s now unlocked from your carrier, adding a plan can be as simple as downloading a new eSIM. You could also use a physical SIM if your phone has an open slot.




A backup SIM may be more useful than you think

Make sure you have a connection wherever you go

Your phone must be within range of a cellular tower managed by your carrier or a roaming partner to use data. Most people are within range of one or multiple towers, so your carrier can be an afterthought if speeds are decent. Still, relying on a single carrier also means a temporary outage can impact your day. Wi-Fi can keep you connected while the network is out. However, if you can’t find a connection, you’re out of luck until the network comes back online.


One thing that surprises me when there’s an outage is how people complain that they run a business from their phone and can’t work when the network is out. If you take your business seriously, don’t build it on a single point of failure with only one carrier. Before complaining that you lost thousands in contracts because of an outage, consider spending $10 on a backup SIM.

Opt out of your carrier’s next outage

While they don’t affect all customers, cellular service outages aren’t as uncommon as they should be. Verizon had a major outage in September. It wasn’t the only one with outages this year. Outages like this are tough because, while many of us use Wi-Fi at home, our data connections get a workout while we’re out. Many of us have come to expect Google Assistant or at least Google Maps to be available at a moment’s notice.


Do you work from the road, like a freelance technician? When you don’t have phone service, you might miss job updates, be unable to take payments, or be unable to contact a client. With a backup SIM on a different network, there’s a chance you can make your call or use a backup form of communication. If you set up call forwarding and that system works properly, you can take calls from your primary number.

Better coverage when you’re traveling

AT&T international coverage map over Europe

The Big Three carriers have made progress with coverage for most people in the country. Still, there are areas with dead zones on every carrier. For example, if your primary SIM is on T-Mobile and data performance isn’t good enough to complete your task, you can switch to a backup SIM in seconds. Plus, if you don’t want your backup SIM active all the time, you can switch it off when you don’t need it.


This could also be useful when traveling out of the country. Some carriers offer better international coverage than others. For example, a carrier like US Mobile has affordable international data add-ons and offers one of the cheapest plans for a backup SIM.

Keep working at work

You don’t need to view your second SIM as a backup plan if you want to keep your work and personal numbers separate. Using your personal number for some freelance work every so often is fine. However, if you use your personal phone for work, switching off a SIM can give you time off after hours. If you think you get a lot of SPAM calls now, try putting your phone number on a website for your business. It also looks more professional if you have a separate work phone number.

What should you look for in a backup SIM plan?

You don’t need a ton of data on both of your SIMs

A Google Fi Wireless SIM package held in front of a Pixel 8 Pro retail display.


Speaking of plans, you don’t need two massive unlimited plans on your phone since, most of the time, you can use data on your main SIM. For a backup SIM, you can get a lighter plan, such as US Mobile’s Light Plan for $10 per month or Google Fi’s Flexible plan for $20 per month if you want access to international data. Fi’s service is also a nice choice because the carrier allows you to pause your service from the app without canceling if you have a month or two when you don’t need the service.

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One thing to remember is that prepaid carriers use one of the Big Three networks, with Boost Mobile heavily relying on other carriers for much of its coverage. Having a SIM from a different network makes sense. That way, you have the best chance of staying connected if something is wrong with a tower.


Your phone is probably ready for a second SIM

If you have a phone from the past few years, it’s probably ready to accept a second SIM. This is often a combination of a physical SIM and an eSIM, but some phones can accept a second physical SIM. Using multiple SIMs is a new concept in the US. It isn’t a new concept around the world, where traveling between countries is common or carriers are regional. Quick eSIM services like Sailly and Airalo make getting a gigabyte or two of data quick, easy, and (reasonably) cheap.

By Everett