Cellular carriers around the world have increasingly let us bring our phone number with us when we travel outside our home country without paying truly exorbitant rates—sometimes they even include more than minimal levels of voice, texting, and data in our basic service plans or for a small fee.
But if you’re traveling beyond the land in which your phone number is a local or national call and swapping a SIM or other module on arrival to obtain a local number and data service, what happens when Apple prompts you to enter a second authentication factor for your Apple ID account? You’ll be fine, but I recommend setting up a fail-safe backup before you travel.
Apple requires you set up trusted devices when you enroll in its two-factor authentication (2FA) system for Apple ID. Any device that you then add to the account—every iPhone, iPad, Mac, and iPod touch—becomes another trusted device. When you log into any Apple device or service, all these trusted devices receive a location alert, asking you to tap or click Allow or Don’t Allow. If you choose Allow, that device receives the code you enter to finish the Apple ID login. An iPhone, iPad, and iPod touch can only be a trusted device for a single account. Each macOS account can act as a trusted device for a unique Apple ID, if desired.
For backup purposes, Apple also allows and encourages you to add trusted phone numbers for which you specify whether you can receive a text message or an automated voice call. You can use these numbers to receive a texted or spoken version of the code. Trusted numbers can be used multiple times across Apple ID accounts, and those accounts don’t have to belong to the same person.
When we travel, we may not carry with us more than one trusted device, however, making its loss, damage, or theft more critical. Couple that with not having a local phone number if you swap SIMs, and you could wind up locked out of critical services, including email or the ability to mark your devices as lost or stolen via Find Me.
Before leaving your country, therefore, I recommend setting up a free or inexpensive phone number that can receive text messages. Google Voice (free) and Skype (a modest fee) are probably the easiest. You set up the number, and then you can use the steps I just wrote about for adding trusted phone numbers.
When traveling, if you can’t access any trusted device, you can use your Google or Skype account name and password to log into those services at any internet-connected machine. (Make sure and memorize those two details!)
This backup texting number is also useful for other services when you travel. Two years ago, I found myself locked out of approving some bank transactions while in England, because my bank intelligently recognized that I wasn’t near a usual location. The only way to validate my transaction was to receive a text—at a number that I didn’t have associated at that moment with my phone! Before my next trip abroad, I’d added an internet-reachable backup texting number.