I have a dual-sim OPPO FInd phone, and I have a USA SIM card with T-Mobile. For the last couple of years I've traveled back and forth to the UK, switching between US and UK sim cards with no trouble. On my most recent trip to the UK, when I returned this week to the USA, I'm unable to make outgoing calls with my USA SIM card. I've tried all of the suggestions on your web page, plus things I've found using Google. No luck. I still can't make outgoing calls.
Best answer by syaoran
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Is the phone Tmobile VoLte compatible?
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It more than likely is not T-Mobile VoLTE compatible. Especially with the more recent changes to Google's implantation. Even older devices that haven't gotten an update in the past couple of years can lose VoLTE compatibility when they were previously.
Asian market devices are most compatible with Asian markets. Even when they are advertised as global devices. That only holds true for some band compatibility and not for VoLTE, VoNR, and VoWiFi compatibility.
I believe it’s VoLte compatible. I have the option to “Use mobile data during calls” which I think is VoLte.
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But it needs to meet Tmobile's standards for VoLte.
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Different carriers use different implementations of VoLTE. T-Mobile has always used Google's stock implantation of VoLTE. The option to use data during a call can be for a few different reasons, like when using dual SIM. It will use the SIM not in use for the call for data usage as long as the call is in progress.
Is there any sort of diagnostic check I could run to verify compatibility with VoLTE? I’ve done some internet searching, but haven’t found anything useful.
I deeply appreciate your help with this, by the way.
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When you're in the USA is the VoLte greyed out?
It’s not. I’m able to enable it or disable it. It isn’t listed as “VoLTE”, but rather the option is “Use mobile data during calls” (and in the description, it says “When you are in a VoLTE call using...” so I assume this is the right setting).
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It’s not. I’m able to enable it or disable it. It isn’t listed as “VoLTE”, but rather the option is “Use mobile data during calls” (and in the description, it says “When you are in a VoLTE call using...” so I assume this is the right setting).
That is a separate setting. Even if the option to enable VoLTE was present, doesn't guarantee it will work. There are tools to unlock those options, even if it won't work. Your device is a dual-SIM device. The option to enable data during calls will be available regardless.
In that case, I can’t seem to find the enable/disable VoLTE setting.
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In that case, I can’t seem to find the enable/disable VoLTE setting.
If you can't see it. Your device does not support a compatible version of VoLTE for that carrier.
Does that imply that my phone isn’t going to ever work with T-Mobile for voice calls?
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Does that imply that my phone isn’t going to ever work with T-Mobile for voice calls?
Yes. As of last year, VoLTE is now required to make and receive calls on the T-Mobile network. No compatible VoLTE on your device means the device is no longer compatible with T-Mobile USA or any US based cellular provider’s network.
Does that imply that my phone isn’t going to ever work with T-Mobile for voice calls?
Yes. As of last year, VoLTE is now required to make and receive calls on the T-Mobile network. No compatible VoLTE on your device means the device is no longer compatible with T-Mobile USA or any US based cellular provider’s network.
Thanks so much for taking the time to think about this and send really informative replies. I have spent so much time (including multiple phone calls with T-Mobile tech support), and made zero progress. It seems that you’ve been able to diagnose the problem using only my minimal and not-well-informed descriptions of the problem. Many thanks for that.
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I used to be a huge fan of Xiaomi phones but they have the same issue, even with the global firmware. As more and more devices from Samsung and Apple offer dual-SIM via one pSIM and one eSIM or dual eSIM capabilities. That has helped those of us a lot that would otherwise have to carry two devices.
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