Can I do this with a T-Mobile eSIM and use whatever physical SIM I buy, say in Hong Kong, and make domestic US calls for free? If so, how?

Which phone will you be using? iPhones have the most models with capability for this setup. Very few Android models apparently support this capability which is surprising since the feature isn’t unique to iOS but dual sim phones.

I have the iPhone 14 Pro Max and Pixel 7.

My iPhone 14 is esim only. I have used my domestic esim with a local esim to make domestic calls without roaming.

Does HK operators offer esims or physical sims only?

Pixel 7 should work with backup calling and does have a physical sim slot. Is your domestic service using an esim?

Yep, but keep in mind that Samsung phones didn't even start to support eSIMs until the last few years. Hopefully, these features will make their way to additional Android models in the coming years. Apple's push to eSIMs will also get more carriers onboard with eSIMs.

I have a foreign iPhone 14 Pro Max. I decided not to buy mine in the US because it's eSIM only. It's not convenient as large parts of the world still use a physical SIM card.

Pre-pandemic, I was still able to buy a physical SIM at the store. In Singapore, I can still buy a physical SIM card.

Domestic, I'm using T-Mobile and AT&T.

Isquare,

Your iPhone 14 with sim tray should still be able to use dual sim service from either the esim + sim card or dual esim, like the iPhone 13 US model. Will that version of iPhone only run dual sims with 1 sim card and 1 esim? I had a iPhone 13 US model and it worked fine on dual esims.

Or, have you considered just buying an esim from someone like Airalo that roams in Hong Kong and run that as a dual esim with T-Mobile esim when in Hong Kong? Any dual sim configuration you use will permit the IMS function, and allow simulated WiFi calls to and from the US without charges. It's easy to set up and use, and you can practice if you have two lines available for testing prior to your departure. In the States, US Mobile has a $5, 30 day esim available with 500Mb, 500 min. & 500 texts that won't break the bank. It runs on the Verizon network I believe, so service should be reliable, depending on your location.

Move your domestic sim to esim and enable IMS on the iPhone. As draver suggested you can test the configuration using domestic sims before your trip for either of your phones.

Have a Pixel 6 running Android 13. where might I find the IMS settings on this (US) phone. ?

iPhone 11 - physical SIM
 

Hi,

Longtime lurker here. I have a new iPhone 15 on its way but due to a problem with AT&T it will not arrive in time for my Italy trip in 2 weeks.
My iPhone 11 does have a physical SIM and a second slot for another one.

We fly into Rome and depart for Florence on the train. Upon departing Florence several days later I will pick up a car and we have several days of free time in Tuscany, with our hotel located in Siena. I imagine I will rely on Waze or Google Nav quite a bit.

What is the best method/company in Italy for me to get a local SIM for a 10 day trip?

Thanks in advance for your assistance.

I believe that in order for backup calling to work on the Pixel the data sim cannot be roaming. So if the data SIM is an eSIM, it may not work because the eSIM might be roaming. With the eSIM vendors, e.g., Airalo, an eSIM might be sold for use in a country but might still be seen as roaming in that country.

That used to be true, but no longer is. They changed it a year or more ago. Pretty sure they fixed it on all models, but at least Pixel 6 and later.

I've successfully used Backup Calling on a Pixel 7 over a roaming data eSIM.

That's great that they changed that - it might have made sense before the ubiquity of roaming eSIMs.

While I'm checking out things to find out what works and what doesn't - it it still correct that background calling does not work in US model Samsung Galaxy phones (I know it has worked on non US Galaxys for a while)?

That’s good for consumers with additional phone option besides the iPhone and the ability to use an MVNO like Mint when traveling internationally