iPhone XS Max dual Sim roaming issue

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Hi .... I am using iPhone Xs max dual sim (2 physical) since last month. I am using it at bangladesh but bought it from hongkong (Model: MT762ZA/A). Since last 20 days many people told me one of my sim was unreachable or they need to try more than one to get connection. I tried everything in settings and also replaced both sim cards.

Please help me to resolve this issue

Thanks

Had the same issue on a recent business trip to Shanghai where I was using a HK/China SIM in slot B and my normal Hong Kong Smartone SIM in slot A. The card in slot B required data roaming to be enabled as its primary country is HK and not China. Prior to enabling data roaming I made sure to switch data to the HK/China card and make my normal HK card the "voice" line.

To my surprise, I was charged for daily data roaming on the HK card despite routing all data through the other SIM - or so I thought.

Called Smartone today to dispute the charges, explaining the problem to them. They were already aware of such cases and were happy to immediately credit my account for the full roaming plan charges. Further, they advised that Apple had told them that his issue is resolved in iOS 12.1 but recommended to remove the HK SIM card next time if the other SIM requires data roaming to be enabled. Obviously, this is a poor solution and defies the whole point of having dual SIMs in the first place (at least for my travel use case).

So I recommend you get in touch with your mobile phone carrier to contest the charges and upgrade to 12.1 if you haven't done so already!

I am having the same issue, but with iOS 12.1.

I live abroad and have the eSIM on the local carrier selected as Primary with a European physical SIM in the slot as Secondary. Roaming is switched OFF.

Despite all the settings and the display not showing 3G or 4G connections on the Secondary SIM, the same gets ridiculously charged for Data Roaming (always for extremely small amount of data, in the range of 0,1 to 3 kB).

I am running the latest iOS 12.1 since before the eSIM was set up on my phone, so that is not solving the issue.

I am in contact with Apple but they seem to not be able to come up with a solution while running blind troubleshooting (Network resets, Phone resets, iOS re-download etc.).

For the time being I have removed the physical SIM card, only working solution I can find, quite unacceptable for an iPhone XS and its cost.

The small roaming data issue (0.1-3K) is due to the roaming authentication mechanism. When a sim with data roaming capability reach another country, it will automatically make use of the foreign local cellular network to send a request checking whether the sim is authorized to use data in that country, despite what you've set in your whatever phone. That request consumes the small roaming data, and is invisible to user. That's why users are advised to remove the sim.

I just told my carrier to disable data roaming and only enable voice roaming to avoid dispute.

My problem is with eSIM. I purchased my Xs Max from Ooredoo Qatar, and I enabled eSIM and traveled to Tanzania. Phone worked fine in roaming mode in local carrier (Airtel). But since I am back in Qatar, all my local call shows as coming from Tanzania. It just shows local number (which normally shows the names from Contact), and Tanzania written underneath it. Carrier selection and all setting show as connected to Ooredoo - local provider. I have a case opened with Ooredoo.

Sharing as FYI.

This is soo simplee and sweet ..

under yr mobile data option on yr phone . Thr is a switch of Mobile data switching .. this switches yr mobile data to anthr simcard when the other sim is on a call ... i hope u got this easy xplantion ..

jz switch that off .. and never have the issue !!!!

Solution was to re-insert original SIM (from Ooredoo) which created another plan, then remove the SIM. Or according the technical support, you have to delete the eSIM plan, and recreate eSIM plan again. I guess this going to be a challenge whenever you roam another country.

I have similar problem. When I select 'Default Voice Line' in Cellular setting, I found that all of my contacts do not switch to Default line which I have selected but few still dial from the sim which is not default sim. This has costed me heavily on roaming charges.

I found that when I was in earlier country which ever calls I made from my that country sim and the call are in Recent call list, still remain on that country sim and do not follow my selection of 'Default Voice Line'.

This is a big defect in UI of iPhone and need urgent correction.

I have the same experience. The auto Last Number used picks up my home number but I would expect when default line is set this should switch all numbers to the travel sim. Yes you can number by number go through your contacts and set to “Always Us” but this is just non-value added.

Default should mean Default.

Facing the same issue, default voice line is getting over ridden by the last call or interaction made with a certain contact. If a contact calls me on Sim A and i have Sim B as default voice line, if i try returning the call, default voice line will be ignored and call will be made from Sim A. And if you happen to be in roaming zone then be prepared to pay heavy roaming charges. The only work around observed is to keep clearing the recent call list so that any and every new call initiated from your phone is from default voice line which is highly inconvenient to say the least. Android has this implementation sorted out for so long, why can apple not fix it in their top of the line software customised for their own hardware. Also data usage for different sim cards is not shown differently and its shows combined data usage of both sim cards which again leads to confusion while roaming or having limited data plans or else one can keep going to individual carrier applications to check the usage. This needs to be sorted out on priority.

Yeah, that is what i have posted but how is that a solution or fix, its a temporary work around at best. One can not go on clearing recent call list after every incoming call while roaming. All this on a dual physical sim model and even then few contacts are remaining on non default sim.

I have exactly the same problem. IOS 12.1.2 on an iPhone XS. I have data only active on the eSIM, but daily, a few Kilobytes, pass over the physical SIM. I have Roaming deactivated, and also "Cellular Data Switching" is off!

To avoid the roaming costs, my only option is now to switch off the physical SIM completely.

But what's the point in having a Dual SIM phone then?! Did anyone got some news on this issue?

Incurring costs all the time while I travel. Even after clearing recent callls, my phone still reverted to UK sim even though default is set to US sim.

My UK account shows data used as well even though roaming switched off and so is data switching.

Back in UK soon so will be calling Apple. Someone has to fix this issue.

To me, they have designed the dual sim functionality purely for the people that have business and personal mobile numbers in their home country. This functionality is not working for international travellers.

Looks like i me I am going back to changing physical sims - so AT&T likely going to charge me again to switch back to a physical sim.