Do you have a phone with either a dual SIM tray or eSIM support? You obviously know that it allows you to get a second phone number, but a second SIM opens a world of possibilities you may not have realized. Let’s look at some real-life, meaningful use cases beyond the obvious stuff like having a backup number.

If you have a recent phone, there’s a very good chance it has both a physical SIM card and eSIM support. Otherwise, everything below should work whether you have a dual SIM tray or eSIM — and users of an eSIM-only phone can also likely try these recommendations. Of course, you’ll need an unlocked phone, since providers like Verizon will prevent you from adding a secondary plan that’s not with them or their partners. Consider using your second SIM for the following to make your phone just a tad more useful.

When traveling abroad, one of the items on your checklist when arriving in your destination country is probably to drop by an airport kiosk and buy a temporary SIM card with a preloaded data plan for the duration of your stay. There’s really almost no need to do that anymore. Instead, you can keep a travel-only SIM that you activate when abroad and then disable when you get back home, buying data plans as needed for whichever country you visit. It’s likely going to be much cheaper than the often expensive rates at the airport, and it means you’ll have data the instant your plane touches down to catch up on messages and start booking a taxi.

One that I’ve personally used in multiple countries with no issue is Ubigi, an eSIM-only carrier offering affordable data plans for a long list of destinations. Once you install the eSIM, all you have to do is buy a data plan for wherever it is you’re going and then activate the eSIM when you arrive. It’s a data-only plan, so there won’t be an extra number on your phone getting calls and texts. Ubigi is just one option in a sea of competitors that provide a nearly identical service, so definitely shop around.

What if you’re looking for an actual physical SIM card for your dual SIM tray, or you need to free up your eSIM for something else? There are other companies that offer physical SIMs, too. We recommend OneSimCard, which has high ratings on Trustpilot — though again, shop around if you see better rates.

Although cellular reception over the years has improved in the U.S., it’s still totally normal to have a phone plan with a dead zone where other carriers give strong coverage. You can use CoverageMap to see your own. Anyway, dead zones can be more than just an annoyance if you need to stay connected for work or be reachable during an emergency when traveling from city to city or state to state. That’s where a second phone plan can really come in handy.

There’s no need to go with an expensive plan. Grab a cheap phone plan from one of the many U.S. budget carriers, ideally finding something that overlaps with those weaker areas and dead zones. Some carriers let you customize your plan by stripping it down to a bare-bones data-only or voice-only configuration. $6 is not bad at all if it helps extend your coverage and give you peace of mind.

Aside from the extra cost, there’s one downside to keep in mind: Your battery will drain a little faster when running two SIMs. That battery drain may be exacerbated when your phone is in a poor-signal area for that secondary network, even though the primary one gets great coverage. To mitigate this, you might temporarily disable that secondary SIM when it’s not needed. Setting up Wi-Fi calling may also help in situations where the signal is weak.

A burner number (a secondary, throwaway number) seems like something exclusively for a drug dealer, a spy, or a womanizer. We’d argue that in this day and age, with incessant robocalls and increasing AI voice cloning scams, having a number that you can give to anyone you don’t trust is actually the smart choice. So anytime a website you know will send you marketing text messages asks for your number, or an account requires it during sign-up, or someone you don’t like is hitting on you, you’ll be glad you had it. Then, you can reserve your real number for your close inner circle of friends, bank accounts, and anything else that’s of supreme importance, keeping it “clean” of spam and scams.

Again, go for a cheap-as-dirt plan here. Tello allows you to build a 300-minute, no-data plan for only $5 a month. Since Tello uses eSIMs, it’s easy enough to burn a number and restart with a fresh one if necessary. Tello also offers physical SIM cards. Just be aware that Tello only allows you to change your number once for free.

Ideally, you’d have a work phone with work contacts and work apps that’s entirely separate from your personal phone. Not all of us are that fortunate. We all know at least one person who’s unable to fully detach from work off the clock because their personal phone and work phone are one and the same. A second SIM card or eSIM (and just a few changes to your settings) can create a pretty effective wall between personal and work life on a single device without making you any more of an unwilling workaholic.

Obviously, having two separate numbers naturally separates your life into two halves. But on both Android and iOS, there are settings that let those two numbers coexist in the same space while establishing clear digital boundaries. Both Android and iOS let you choose the default number to use for texts and calls; both also let you (on Android, this depends on your flavor) choose which SIM to use before every call or text.

Further, both Android and iOS support Focus modes that can control how and when notifications arrive, making it easy to silence work contacts during off hours. Depending on the phone you have, you may also have access to intelligence features that let “important” notifications pierce the veil and reach you in your free time. Android has an additional leg up here with the option to create a second user profile (and dedicated work profiles) on the same phone, further confining your work to its own little unobtrusive box. The point is, software-based work/personal separation features are so good these days that a separate work device almost seems like overkill.

Anyone who has lived abroad knows that getting your visa, exchanging money, and buying the right gadgets for remote work is the easy stuff. It’s the little things you don’t think about that creep up on you and cause the biggest headaches. For example, the fact that many online accounts (like bank accounts) require you to have a phone number based in your home country and reject app-based VoIP numbers like TextNow. It’s made worse by the fact that major carriers may charge an exorbitant amount to use an existing number abroad. The secret to avoiding those costs and still having a working phone number for occasional OTP codes and customer service calls is using Wi-Fi calling on a second SIM.

Basically, Wi-Fi calling is when your SIM card routes texts and calls over the internet rather than through a cell tower, giving you full access regardless of which Wi-Fi network you’re connected to or where you are. Just make sure you have a carrier that supports it and doesn’t impose restrictions on using texts and calls internationally. Usually, all it takes to activate it is a simple “Wi-Fi Calling” toggle in your mobile network settings. Since you’re probably paying for a mobile data plan in your current country of residence, purchase a cheap plan (Tello’s $5/month plan supports international Wi-Fi calling, for example) just to get your calls and texts.

Based on my own personal experience, this is the best way to live abroad while maintaining a fully functional number. I’ve had mixed success with services like Google Voice. My only big recommendation is that you set up the SIM in your home country before traveling abroad, as setting it up internationally can be dicey — perhaps impossible.