As a general rule, I’m against an alien takeover of our planet — unless they bring along one thing: a global wireless system that would simplify the endlessly complex world of options for using cellphones abroad.
Prices for calling, texting and using data overseas continue to fall, but the larger system relies on a haphazard and incomplete set of agreements among wireless companies from every country on earth. That makes finding the cheapest option that will (mostly) satisfy your needs still a complex task, depending on where you’re going, for how long and with whom.
First, let’s go over some basic rules for saving. If you don’t have a foreign plan, keep international data roaming off (and check to see how much it will cost you per minute if you pick up when, say, your mother calls). To limit data use, don’t let your apps run in the background and adjust your settings so they don’t refresh. Browse the Web using an Opera app, which uses less data. Pick a messaging app (WhatsApp, Viber, Skype) so you won’t have to pay for texts, and make sure your friends and family are all on it. (Most of these now allow free calling among users.)
Now I’ll break down your options into categories — but, fair warning, you’ll have to do some follow-up work, diving into the sometimes opaque websites of the service providers to figure out the most economical option for your needs and destinations.
Stick to Wi-Fi
Those not addicted to social media or needing to be connected at all times to family or office can stick with free Wi-Fi hot spots — though know that it’s a calculated risk. If you do need to use the phone in an emergency, it can cost you: $5 a minute is not uncommon, and smaller service providers, like Cricket Wireless, offer limited or no service abroad.
And Wi-Fi dependence brings two more problems. First, availability varies greatly by country and region (you can check overall coverage on Wi- Fi finder apps or sites). Second, using public Wi-Fi can expose you to hackers; avoid it especially if you’ll be typing in banking and credit card information. If you want to eliminate much of that risk, read on.
T-Mobile and, since April, Sprint offer free 2G data service, free international text messaging and 20-cent-a-minute calling — with a couple of catches. First, it doesn’t work everywhere. Sprint’s plan currently covers just 22 countries, though that list will grow.
T-Mobile’s roaming is impressive if a bit overstated, covering 120 “countries and destinations” — not to be confused with 120 countries (Easter Island? Svalbard?) Check the lists to make sure your destination is included.
And, of course, that 2G connection can be painfully slow, though it is usually fast enough to use email and messaging apps. In my experience with T-Mobile, you’re frequently bumped up to 3G or 4G, but occasionally can’t connect at all. (If that happens, find free Wi-Fi and call your carrier through Skype for help.)
Upgrade Your Package
You can pay Verizon and AT&T for higher-speed international roaming packages, or pay Sprint and T-Mobile to upgrade to faster data. Some of those options are pretty good deals: Verizon’s monthly add-ons start with 100 megabytes of data for $25, and you can add 100 minutes of talk and 100 texts for an extra $15. (Again, check the list of countries.) AT&T has similar data packages, but they include unlimited texting. Both deals currently include free access to networks of paid Wi-Fi hot spots around the world. T-Mobile’s upgrade plans are more appealing than Sprint’s: 200 megabytes of high-speed data over one week for $25, good for a short trip.
You’ll also keep your own number, which means you won’t get a local number. But that is far less inconvenient than it used to be now that almost everyone abroad is using messaging apps.
International SIM Card
Lots of companies sell SIM cards that can be used in most of the world (or cheaper ones for Europe only): OneSimCard, Cellhire, Cellular Abroad’s National Geographic SIM, Telestial, the list goes on. Cards themselves usually cost about $20 to $30, often including some credit. And rates vary vastly by company and country, so make sure to check websites for details.
Pay special attention to the varied payment structures: You might prefer to prepay and let your balance tick down with use, buy a big chunk of data that will last for a while (but might go to waste), or pay per day for unlimited data. Also check if you can monitor your usage in real time, and take care if you choose to do automatic top-ups; it would be a shame if you were charged $79.99 for an extra gig as you waited in the airport for your flight home.
With a foreign SIM card, you won’t receive calls or texts coming into your home number. If that’s important, you can set up forwarding, which doesn’t always work, or frequently switch cards, which is a pain. You can get a dual-SIM phone (not for iPhones, though) or a two-SIM adapter, which can be awkward.
The smoothest solution is KnowRoaming’s international SIM “sticker,” which you attach to your current SIM card, magically turning it into two. The foreign SIM activates when you land in a different country, but you can manually flip back to your home SIM. It costs $29.95 plus usage, and rates are competitive.
If you’re headed to one or just a handful of countries, especially obscure ones not included in the above plans, consider purchasing a local SIM card.
The cheapest way to do this, at least theoretically, is to buy one when you arrive. This often costs just a couple of dollars (plus prepaid credit), but the ease of doing it varies greatly, depending on the registration process and access to English-language instructions.
Your other option is to order the country-specific SIM card before you leave, meaning it’s already registered and loaded when you land. Cellular Abroad, for one, offers a French card that gives you a month of unlimited calling and texts, one gigabyte of data and 110 minutes of free calls to the United States and Canada for $69.95 — not cheap, but perhaps worth it if it fits your needs.
Many of the same companies offer data-only SIM cards that are cheaper, generally, than those with a local number for calling and texting. They’re largely aimed at tablet users and are particularly attractive if you have T-Mobile or Sprint on your phone for cheap calling and free texting. Cellhire, for example, provides 200 megabytes of data for $25; it works across Europe and lasts 30 days.
There is also a free data-only SIM coming soon. It will be offered by Freedom Pop — which also provides free, but limited, domestic cell service — and includes 100 megabytes of high-speed data a month in a small but soon-to-grow list of countries.
For groups or travelers with multiple devices, a big money saver is to take those data-only SIMs and stick them in a Mi-Fi device — a personal Wi-Fi hot spot that is often less than $50. If your group is big enough and can live without a calling plan, that reduces costs significantly.
So, yes, it’s complicated; yes, you need to do your own research; and even if you’re thorough, there will often be hiccups on the road. Maybe we should try to get in touch with those aliens after all — if only we knew which
SIM card has the best rates to the Andromeda Galaxy.
A version of this article appears in print on June 21, 2015, on page TR2 of the New York edition with the headline: A Phone That’s a Worthy Companion Abroad.