I never experienced your scenario with my iPhone. I use the local sim to send and receive WiFi calls and texts for my domestic sim with no roaming charges? Does your Android phone have this option?

My work Pixel is supposed to have this capability but it doesn�t always work.

Not all plans / providers offer WiFi calling, or at least the ability to block international calling / roaming calling capabilities on the providers side.
(With just WiFi calling too, you may not have a data connection for whatever reason.)

So when a call comes in on the �home� line, some people will just pick up�

Trust me, I�ve seen my dad rack up $30 calls of <10mins more than a few times; his roaming fees in a few months have been higher than than the base plan itself. The mobile provider knows what they are doing�

Yes, you can pick which SIM to use for each call and each SMS. For data, only one SIM will be active at a time. The bigger challenge will be getting the eSIM from Vodacom and activating it outside SA, which may not be possible--some carriers' SIMs can only be activated on the 'home' network.

On iPhones and most recent Android phones, you don't just turn off data roaming, you can switch off the SIM altogether even for physical SIM cards. Only on older Android phones do you actually have to remove the SIM to disable it. On iPhones, the toggle to switch a SIM off only appears if you have at least two SIMs.

Your dad was scammed in his home country by the quick call hang up which he returned to incur the charges. That�s an old scam which is blocked on my plan.

When traveling internationally, my domestic esim uses the data of the local esim for WiFi calling. Absolutely no reason to remove/disable my sim with this setup. My son has been deployed to Europe and hasn�t incurred any international charges while traveling in Germany, Latvia, Poland and the Rep of Georgia.

With my iPhone 15, there is an option to turn off cellular data to restrict all data to WiFi if only one sim is active. Offline maps still work since the phones are GPS capable without cellular data.

I think that was added by an iOS update somewhere along the way; my XR has it too but it definitely didn't used to be there.

AFAIK you still can't switch off your SIM altogether if you only have one, though you can definitely switch off all your SIMs if you have at least two. I'm not going to delete my eSIM collection to find out

edit: my work iPhone 14 (iOS 17) has only one SIM and indeed there's no toggle to switch it off altogether.

If I had no experience with eSIMs and I looked at this thread I would conclude that using eSIM is really complicated and fraught with problems. Fortunately I have lots of experience, in many different countries, and my reality is that it is really easy, cheap and convenient.

Not a scam� well, except for the rip-off charges from the phone company.

He gets legitimate calls from someone (relative, friend, old business contact, bank, utility, whomever) on his home phone number, since they don�t know he�s travelling. He picks up, since someone wants to contact him, but doesn�t look at the screen to see whether it is incoming on the home number or the local number or even WhatsApp/Skype, and then continues the call without thinking further � until he sees the monthly bill.

Most such calls, the mobile provider charges ~$3/min, or more if in a less-travelled country (Greenland: ~$5), despite that it probably now costs them pennies on the dollar, if that.

The regulator has no interest (unlike in the EU), and the home and roaming providers happily go on sharing the fees between them�

I�ve made some recommendations to my dad� but he doesn�t want to change. *sigh*

(Thankfully, I�ve gotten myself a plan with WiFi calling, doesn�t happen to me�)

It is most definitely a scam call received with a quick hang up. The receiving part then presses call on the Home Screen.

One ring scam call back

esims are easy to use. All these scary warnings are things I have never experienced. I buy my esim before leaving and activate over WiFi while walking to passport control or baggage claim. I am up and running before leaving the airport: I usually spend less than $30 for a 2 week trip.

I don�t dispute that there is such a scam, but my dad was not stung by those�

Again, they were all known contacts calling him: the calling ph # & length of each call was listed under �Incoming calls� on the itemised bill.

The problem for him is the (published) ridiculously-high fees of roaming calls charged by the home-country mobile provider, nothing else. (Well, maybe his lack of attentiveness too�)

Definitely convenient, relatively easy but not necessarily cheap unless you only buy a couple of gigs of data at the most.

You pay a premium over local SIMs for the convenience.

Right now, most of the eSIM providers are third parties buying bandwidth wholesale and reselling to consumers. If and when carriers sell prepaid data eSIMs directly to the public, at the same prices as their physical SIM prepaid data, then it becomes a no brainer to get eSIMs.

And with some companies like Apple now only supporting eSIMs, looks like the days of the physical SIM cards could be numbered.

that’s not always the case. For Japan and UAE an eSIM ist cheaper for example.

I believe Airplane Mode switches Off all cellular functions on single line iPhones, with either esim or psim.

If you have WiFi calling you can then turn on WiFi and use the phone without using cellular service.