iPhone XS Max dual Sim roaming issue

I travelled to Japan last weekend and used a foreign roaming Sim as travel Sim for data usage. On arrival in Japan, I disabled airplane mode, changed mobile data to travel Sim in settings, then activated data roaming.

With mobile data set to the travel Sim, data usage is not supposed to be incurred on the primary Sim. I received messages from the primary Sim carrier that my data roaming package was activated. After arriving home, I switched the mobile data back to the primary Sim, It shows that I've used 165GB of data in Current Period Roaming. It's not even possible for a 2-day trip. I switched mobile data to travel Sim and the figures were the same.

I called the carrier to check the data roaming history, 27KB was used on the day of arrival in Japan. Therefore I have to pay HK$198 flat rate for the data roaming package. I requested the carrier to waive the charges and they did, now they're only charging for the 27KB used at normal rate which is down to around HK$3.

So there are two problems found in this issue:

1. Switching mobile data from A Sim to B Sim does not fully deactivate data usage on A Sim

2. The mobile data usage figures seem to be inaccurate

Any fix for this? I upgraded my phone to iPhone XS Max because I travel a lot and I want to switch Sim seamlessly without physically replacing Sim cards, but it turned out disappointing. The carrier waived my data roaming package charge because I've been using their services for 10+ years without such history regarding data roaming. I don't know if they'd waive the charges the next time. If I need to remove the primary Sim everytime while travelling, what's the point of buying a dual-Sim phone?

iPhone Xs Max, iOS 12

Posted on Sep 25, 2018 5:04 AM

23 replies

Jan 16, 2019 6:08 PM in response to SanjayGoenka

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.

Jan 16, 2019 6:23 PM in response to sandygoodwin

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.

Oct 4, 2018 7:13 AM in response to Kartoffelplastik

I am hoping someone from apple can shed lights on this. I was asking AirSIM this question and they suggest I remove the hk sim whenever I travel to avoid the phone getting confused!! 😱

Fan1226

Level 1

4 points

Oct 21, 2018 9:53 PM in response to lobsterghost1

I got same issue and just report to Apple. Telecom operations rejected to reduce the roaming charge.

Jan 16, 2019 6:17 PM in response to K_Maheshwari

Since found another thread that has a workaround. You have to delete all recent calls. Then all calls will be made on the Default line.

Jan 16, 2019 6:24 PM in response to K_Maheshwari

Agree. But unfortunately until someone at apple develops a fix we are stuck with it.

Nov 5, 2018 9:04 AM in response to Kartoffelplastik

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

Ivano77

Level 1

4 points

Nov 14, 2018 11:06 PM in response to pmansari

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.

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iPhone XS Max dual Sim roaming issue