Backup phone
 

I have a Pixel phone (A) with a physical T-Mobile SIM, and plan to add a backup phone for my travels.

- Get an used phone (B)
- Transfer data and apps from phone A to phone B
- Test phone B with the T-Mobile SIM
- Return the T-Mobile SIM to phone A
- Get an eSIM (destination country) for phone B, with the same number
- Use phone A for travel, and phone B as backup

Would appreciate comments.

Pixels are dual sim phones with backup calling. Multiple sims can be installed and switched between active and inactive.

Prior to iPhones having IMS, I carried 2 phones and used WiFi calling to avoid international roaming for my domestic sim by using the 2nd phone with a local sim. Many Pixels and iPhones are capable of achieving the same WiFi calling.

What's your threat/usage model?

Backup in case phone is stolen or breaks?
Backup to extend battery life on busy days by swapping mid day?
Only traveling with backup (eg in case of searches by foreign governments)?

​​​​​​​Yes, should have made that clear.

Do you mean to tie two active phone + data (1 physical SIM, 1 eSIM) to the same phone T-Mobile phone number? I don't think T-mobile supports that. Ruminated and was reminded of T-Mobile Digits https://www.t-mobile.com/support/pla...ed-with-digits YMMV https://www.reddit.com/r/tmobile/com...at_is_tmobile/

You could provision a local destination eSIM in your backup phone for use in case phone A dies or gets stolen but it wouldn't get 2FA sms messages, assuming your US bank only knows of your T-mobile number and not using an app to authenticate. You may want to ask T-Mobile if they'd be able to provision an eSIM or backup physical SIM while traveling outside the US if your phone is stolen. Check essential apps/websites requiring 2FA for 2nd auth methods beyond sms & enable them.

I've been travelling with a 'backup' phone for the past few years. Thankfully I've never needed it, but the knowledge that it's there in case my main phone breaks/is lost/stolen/etc is good comfort.

In my case the backup is my old Pixel 5. Fits the bill well as it's relatively small, and supports eSIM (and in my case, only eSIM due to a broken SIM tray!)

I don't have all of my data loaded on it - most of everything that is important can be recovered from the cloud, but I do have it logged into my relevant accounts, and a few key apps installed including Airalo and Firsty (including having a Firsty eSIM installed), my cell phone providers app, Google Authenticator, Google Wallet, etc. Using those apps I can move my primary providers eSIM over to the phone, get a local data eSIM, and have full access to mail/2FA/etc, and potentially even to money via Google Wallet.

Yes, same number on two phones. But only one would be active.

According to AI, "T-Mobile (US) doesn't offer a duplicate SIM card option for using the same number on a second phone, but you can use the Data with Paired DIGITS plan to pair your primary number with a second device for $10 a month, which provides unlimited data at 512 Kbps." DIGITS would be too slow.

My primary reason for wanting the same number on both phones is for 2FA, but I may have to punt. If phone B has a different number, I'll have the backup codes for 2FA.

My phone A has a physical SIM. If it has an eSIM, how would it work? After moving eSIM from phone A to phone B, phone A would have no SIM?

You stated your use case here was if you lost your primary phone. If you phone has been stolen, so has the SIM card so it's not like you could move that over...

Most(*) eSIM providers will let you create a new eSIM on demand and install it on a new phone. Doing this will invalidate the previous physical SIM or eSIM that was used for that number. So 'when' your original phone is stolen, install your cell service providers app on your new phone, go through the process to generate a new eSIM, and the install it on that phone. This'll achieve 2 things - it'll stop your old phones SIM from working (thus stopping anyone running up bills on it, if it's not prepaid), and it'll also mean your backup phone now has that service. Obviously having the relevant apps pre-installed, and confirming that you can login to them without your primary phone (eg, no SMS-based 2FA) would be a good thing to do before you need to do this!

(* Just to be clear - most normal phone companies will let you create replacement eSIM. Most "travel" eSIM companies will NOT allow this as a way of stopping people from sharing their products. If you had a travel eSIM installed at the time, you'd likely need to buy a new one)

If your current phone is not EOL, do you have a lucrative upgrade on T-Mobile? Then keep the current device as your back-up.

You might even just be able to login to your google account on both devices and it syncs apps, contacts, photos, etc. Power on the back-up phone periodically to “sync” or have faith Google back-up will be feasible on a foreign wifi network or cell service.

If you haven’t done so already, you can setup a SIM PIN on the device(s) which ensure the phone is inoperable if stolen. Of course it could be stripped for parts…

T-Mobile has a site that details converting physical sim to ESim. Certain models are supported.

- Can this be done if the the original phone has a physical SIM, as in my case?
- If the original phone has an eSIM, will the "new eSIM" generated on the backup phone be the same?

@Trouvaille, thanks for the suggestions.

My threat model is probably different, but I would recommend downloading only what you need (maps, tickets) on the backup phone, and using that in public while traveling. That way, when stolen, they only have a phone and not a ton of your data.

As questioned in your original post, you won't get a travel e-sim with the same number, but if you copy some contacts, then you can give them your new esim number so they can reach you if it's urgent.

The first question is one for your cell service provider, but most providers will allow you to migrate from a SIM to an eSIM (or an eSIM to a new eSIM). You may be able to do it on their website, or on their app, or it might require calling - it all depends on the telco.

An eSIM is functionally the same as a SIM card, with the obvious exception that it's not physical and thus can't be moved from one phone to another (although some phones actually DO support that, but as you need both phones to do it, it's not relevant here). Moving from a SIM to an eSIM is no different to doing a "sim swap" and replacing your current SIM card with a new one. Everything about your service will carry over (phone number, plans, etc), but nothing else will (photos, data, contacts, etc - all of which are on the phone) - but presuming you have those all backed up with cloud services then you can just get them all back from there.

@S80,Thanks for the comments.