I find that turning off a SIM or eSIM entirely is the best way to prevent any undesired usage. It's a really useful feature. With the current daily roaming rates of Canadian wireless providers ($12/d for U.S., $15/d for international) I prefer to have my home SIM disabled entirely rather than have only specific services (e.g. roaming, data) turned off.

You need a revolution up in Canada. The mobile phone rates are crazy high to begin with, and the roaming costs are even more insane. The US carriers have free Canadian roaming on most of their plans. Canada is the outlier on prices, e.g., look what you can get in the UK: https://www.vodafone.co.uk/mobile/be...topnav~1~1~2~1

Yeah, no kidding. :( Consumer protections and regulations often seem to be a two-steps-forward, one-step-back kind of thing here. I've been doing okay with some travel hacks, such as using free 90-day T-Mobile data plan trials for my U.S. travel. But it's criminal what these companies can charge here. It's especially insulting when you look at countries with similarly low population densities like Australia or Sweden.

https://stacksocial.com/sales/instab...lan-2-gb-month

(instabridge is by Degoo, one of those "lifetime" data-backup companies that have negative reviews

pricing/country/availability from their app is different than from their website

I do this very thing regularly (late-model iPhone).

Furthermore, the carrier I use in my main location outside the USA has a VoIP app, so I can still use their service -- both sending and receiving both SMS and phone calls -- even with that carrier's eSIM turned off. It's handy for e.g. OTP codes for online banking.

Are we talking DIGITS from T-mobile or something different?

I'm talking about an app called DTAC Call.

I've called in to the carrier to disable this feature from automatically activating while out of the country. Chances are the one time charge you'll have to pay for accidentally using the service is a lot less than the 12/15$ you'll have to pay for the day's roaming.

I'm leaving for a 2 week trip to Europe next week and will be primarily in the UK, Germany and Poland. I currently have an iPhone 13 Pro Max with my AT&T service on a physical SIM and plan on using Orange's 20GB Europe Holiday plan while traveling on an eSIM. I'll be starting and ending my trip in London if it matters. That said I have a couple questions.

1. Can/should I install the eSIM before departing the US or would I be better off just installing and activating it once in London? From their FAQ it looks like I can install it before leaving ad once it recognizes a European carrier it will automatically activate. I just don't want to do something that could cause it to activate in the US because I'll need all 14 days the plans offer as my flight home will be on day 14. I'd like to have it installed and working before leaving LHR but in a worst case scenario if I could wait until I get to my hotel. I've stayed there several times and know how to get there.

2. I've seen it mentioned several times that you can enable wifi calling, turn off roaming on your US SIM and use the data from the local SIM to make and receive calls to/from US numbers as if you were in wifi. Is that all there really is to it? I have a Google Voice number that I know I can use over cell data to make and receive calls and texts to the US if need be but I'd rather just be able to use my existing US number since that's what all my friends and family already have.

I'm sure I'm over thinking things as usual but thought I'd ask before doing something potentially stupid.

Regarding your #2 question, the procedure is simple. Leave your US sim set to roam, but select a non roaming carrier for it in Settings, Cellular, AT&T line, Network Selection, Automatic Off. You must then choose a carrier that you have no roaming service with. Probably one of those towards the bottom of the listed carriers. Once selected, your Status Bar at the top of your screen for that line should change to No Service, then after a few moments to Using Cellular Data. This function is called IMS, and works well with a second line providing data. Your AT&T line is using the data line as a pseudo WiFi carrier. Provided that AT&T gives free US WiFi calls, you will have no charges, and on your account those calls will record as made on WiFi. I'd review what the charges are for local (UK) WiFi calls are since your voice line will be active.

You can practice the setup prior to leaving the US if you have a second line available for data. I use the First Responder (313 100) network for my voice line non roaming carrier, since I cannot roam on it. Or, Verizon or Sprint should work in the US for you also.

Thanks for the info. I’ve added it to my travel info. I double checked and AT&T allows calling US numbers from other countries at no extra charge using wi-fi calling. As for any local calls while traveling in Europe I decided to pay the few extra Euros to get their package that comes with a French (iirc) number that gives unlimited calls and texts in 50 different countries/territories which will cover all the places I’ll be staying or transiting.

I'd like to try this before our next international trip but Settings, Cellular, AT&T section does not have a Network Selection option for my iPhone 13 running iOS 16.4.1

Does it need a second carrier eSIM installed first?

This sounds potentially dangerous - if the phone switches networks to the one with service, then you are paying for roaming.
An alternative way of doing this:

• Unconditionally call forward the US AT&T number to a Google Voice number.
• Install GV app on your phone.

Once you've accomplished that (assuming you have data from an esim) you have free incoming calls to your AT&T number (forwarded to the Google Voice app), and free outgoing calls through Google Voice. If you want to call people stateside with your normal caller ID showing, Skype can be set up to show your regular phone's caller ID for outgoing calls.

Do 2FA OTPs get forwarded to GV?

The other recommendation from the Airalo sub-reddit is to get international roaming for voice and data get turned off on your account by calling AT&T. This way, you get either No Service or AT&T WiFi connection on the AT&T "line" when not in reach of an AT&T tower. "WiFi" can be a real WiFi AP or data service from an eSIM on the device.

I haven't tried it myself but intend to.

This is what I am doing for my upcoming trip using Airalo. It just seemed more foolproof to just disallow international roaming so I don't get caught and get a $1,000 bill for checking my email in Bangladesh. I got it disabled via the Verizon chat on the website in about 5 minutes.