Hi,I’m going to visit the USA in three weeks and I’m already looking forward to it. :)During my roadtrip, I want to use my smartphone, a Xiaomi 13, with an T-Mobile-Prepaid-Card. I checked via the IMEI number if my smartphone is compatible with the T-Mobile-Net. The problem is: I got different results. One site told me, the phone was 100% compatible, another side told me the opposite. So I’m a little bit insecure. Has anyone experience with this device or can tell me more?This would be very nice. Thank you. :)

Xiaomi 13 | T-Mobile Community

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syaoran
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5817 replies
4 months ago
5 March 2024

Whether or not the device has the bands needed isn't all of what will ensure it will work. Bands 2, 4, 12, 41, 66, and 71 are the more common bands deployed. There are no guarantees that the bands your device might be compatible with are deployed where you are going to be traveling. The most important thing is, your device must be compatible with T-Mobile's implementation of VoLTE, which most Asian region devices are not. VoLTE is needed to be able to make and receive calls because there are no 3G networks remaining in most of the country for calls to fall back on if VoLTE compatibility is not there.

@syaoran hi can you expand upon what an implementation of VoLTE is and why it isn't universal? I have a redmi note 13 pro + (CN ROM) that worked for a few months before suddenly getting signal cut off (no calls or data).

I couldn't recall whether it coincided with the hyperOS update but I've read some horror stories on forums blaming the update for loss of cellular connectivity. I even paid xiaomi service to downgrade my OS back to miui to see if that would resolve the issue - didn't work.

I was using mint Mobile which works off of tmobile's network, and mint mobile's IMEI checker claims the phone was incompatible even though it worked for a few months, whereas tmobile's IMEI checker confirms my phone is compatible?? Does IMEI compatibility also imply certification or..? Idk if xiaomi phones are even certifiable in the US, but some forums claim their 'uncertified' phones are somehow working...?

I don't know if it was one of your previous answers or some other forum I read where they said flashing a different rom won't change the connectivity settings (I'd have to repay xiaomi service to unlock my bootloader anyways 😒) but is that true? Could my issue really be a hardware problem, or a firmware/software problem? I added a picture of bands compatible according to kimovil for ref. I read one of your comments on another post where you mentioned using 'qpst', is that something that lets you configure the firmware responsible for cellular connectivity or unlocking bands or something...? Is there a mediatek version of that?

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syaoran
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5817 replies
1 month ago
11 June 2024

Android uses profiles that aren't accessible through the OS through normal means, when possible, for a specific implementation of VoLTE, WiFi Calling, and VoNR. Different carriers have different implementations, making the devices more carrier specific or more region specific. Asian implantations of VoLTE, VoNR, and WiFi Calling are not normally compatible with EU and North American regions. This is a carrier.choice.

T-Mobile USA, T-Mobile, and EE as an example, use the same implantation. AT&T USA's implantation is not compatible with T-Mobile's, which makes it harder to use a non-AT&T device on their network. Asia has a more proprietary implementation that is focused towards the market those devices are made for and designed to work in. If they were to use the stock Android implementation that T-Mobile uses, VoLTE, VoNR, and WiFi calling would not work on Asian carriers.

There are tutorials out there including on the official Xiaomi boards on how to alter the carrier profile using root. The issue with that is, that the profile resets to what it originally was every time the device is rebooted or updated. Qualcomm's QPST is the only way to properly set this, but it is not a user friendly tool and can easily brick your device or cause it to no longer be able to connect to any networks. The way the tool works is by writing to the oartition of the device where the modem firmware and configuration is stored, which is outside of the OS. If this gets messed uo, a factory reset will not restore it! This is why I don't talk about it much.

Android uses profiles that aren't accessible through the OS through normal means, when possible, for a specific implementation of VoLTE, WiFi Calling, and VoNR. Different carriers have different implementations, making the devices more carrier specific or more region specific. Asian implantations of VoLTE, VoNR, and WiFi Calling are not normally compatible with EU and North American regions. This is a carrier.choice.

T-Mobile USA, T-Mobile, and EE as an example, use the same implantation. AT&T USA's implantation is not compatible with T-Mobile's, which makes it harder to use a non-AT&T device on their network. Asia has a more proprietary implementation that is focused towards the market those devices are made for and designed to work in. If they were to use the stock Android implementation that T-Mobile uses, VoLTE, VoNR, and WiFi calling would not work on Asian carriers.

There are tutorials out there including on the official Xiaomi boards on how to alter the carrier profile using root. The issue with that is, that the profile resets to what it originally was every time the device is rebooted or updated. Qualcomm's QPST is the only way to properly set this, but it is not a user friendly tool and can easily brick your device or cause it to no longer be able to connect to any networks. The way the tool works is by writing to the oartition of the device where the modem firmware and configuration is stored, which is outside of the OS. If this gets messed uo, a factory reset will not restore it! This is why I don't talk about it much.

I used a Motorola phone I bought in the US for 4 years in India, so is the interregional implementation incompatibility only one-way? Phones from the US will work universally but not the other way around? You also say that Asia's proprietary implementation, if configurable to the stock android implementation necessary for US networks, would no longer work on Asian carriers, but that goes back to my question of how do phones from the US work fine abroad? Also how does international roaming work then if network configuration is device specific?

Userlevel 7

+15

syaoran
Pillar
5817 replies
1 month ago
11 June 2024

Android uses profiles that aren't accessible through the OS through normal means, when possible, for a specific implementation of VoLTE, WiFi Calling, and VoNR. Different carriers have different implementations, making the devices more carrier specific or more region specific. Asian implantations of VoLTE, VoNR, and WiFi Calling are not normally compatible with EU and North American regions. This is a carrier.choice.

T-Mobile USA, T-Mobile, and EE as an example, use the same implantation. AT&T USA's implantation is not compatible with T-Mobile's, which makes it harder to use a non-AT&T device on their network. Asia has a more proprietary implementation that is focused towards the market those devices are made for and designed to work in. If they were to use the stock Android implementation that T-Mobile uses, VoLTE, VoNR, and WiFi calling would not work on Asian carriers.

There are tutorials out there including on the official Xiaomi boards on how to alter the carrier profile using root. The issue with that is, that the profile resets to what it originally was every time the device is rebooted or updated. Qualcomm's QPST is the only way to properly set this, but it is not a user friendly tool and can easily brick your device or cause it to no longer be able to connect to any networks. The way the tool works is by writing to the oartition of the device where the modem firmware and configuration is stored, which is outside of the OS. If this gets messed uo, a factory reset will not restore it! This is why I don't talk about it much.

I used a Motorola phone I bought in the US for 4 years in India, so is the interregional implementation incompatibility only one-way? Phones from the US will work universally but not the other way around? You also say that Asia's proprietary implementation, if configurable to the stock android implementation necessary for US networks, would no longer work on Asian carriers, but that goes back to my question of how do phones from the US work fine abroad? Also how does international roaming work then if network configuration is device specific?

The 3 main US carriers all use different implementations. US devices adapt to the carrier SIM put in the device to be as compatible as possible. Then you add in Canadian and Mexican roaming as well as people traveling a lot between the 3 countries in North America, which makes US devices very carrier friendly, even outside of of North America. Asian devices makes can add more North American compatibility to their Android versions but they don't.

India devices are also very versatile because of the sheer amount of regional carriers that all have very different deployments. I have personally rum the India firmware on my OnePlus 7 Pro and OnePlus 8T and had no issues connecting to T-Mobile and Canadian carriers.

Android uses profiles that aren't accessible through the OS through normal means, when possible, for a specific implementation of VoLTE, WiFi Calling, and VoNR. Different carriers have different implementations, making the devices more carrier specific or more region specific. Asian implantations of VoLTE, VoNR, and WiFi Calling are not normally compatible with EU and North American regions. This is a carrier.choice.

T-Mobile USA, T-Mobile, and EE as an example, use the same implantation. AT&T USA's implantation is not compatible with T-Mobile's, which makes it harder to use a non-AT&T device on their network. Asia has a more proprietary implementation that is focused towards the market those devices are made for and designed to work in. If they were to use the stock Android implementation that T-Mobile uses, VoLTE, VoNR, and WiFi calling would not work on Asian carriers.

There are tutorials out there including on the official Xiaomi boards on how to alter the carrier profile using root. The issue with that is, that the profile resets to what it originally was every time the device is rebooted or updated. Qualcomm's QPST is the only way to properly set this, but it is not a user friendly tool and can easily brick your device or cause it to no longer be able to connect to any networks. The way the tool works is by writing to the oartition of the device where the modem firmware and configuration is stored, which is outside of the OS. If this gets messed uo, a factory reset will not restore it! This is why I don't talk about it much.

I used a Motorola phone I bought in the US for 4 years in India, so is the interregional implementation incompatibility only one-way? Phones from the US will work universally but not the other way around? You also say that Asia's proprietary implementation, if configurable to the stock android implementation necessary for US networks, would no longer work on Asian carriers, but that goes back to my question of how do phones from the US work fine abroad? Also how does international roaming work then if network configuration is device specific?

The 3 main US carriers all use different implementations. US devices adapt to the carrier SIM put in the device to be as compatible as possible. Then you add in Canadian and Mexican roaming as well as people traveling a lot between the 3 countries in North America, which makes US devices very carrier friendly, even outside of of North America. Asian devices makes can add more North American compatibility to their Android versions but they don't.

India devices are also very versatile because of the sheer amount of regional carriers that all have very different deployments. I have personally rum the India firmware on my OnePlus 7 Pro and OnePlus 8T and had no issues connecting to T-Mobile and Canadian carriers.

So when you say run firmware, you mean flashing rom right? Or is it qpst? So have you really not had any experience or heard of success stories of cn devices, particularly mediatek, of being configurable to North American networks? Do you think it would make a difference if I flashed a global rom onto my note 13 pro +? Or is there something more, like a qpst variant for mediatek devices that id have to contact a xiaomi service person to support me with?

Userlevel 7

+15

syaoran
Pillar
5817 replies
1 month ago
11 June 2024

Android uses profiles that aren't accessible through the OS through normal means, when possible, for a specific implementation of VoLTE, WiFi Calling, and VoNR. Different carriers have different implementations, making the devices more carrier specific or more region specific. Asian implantations of VoLTE, VoNR, and WiFi Calling are not normally compatible with EU and North American regions. This is a carrier.choice.

T-Mobile USA, T-Mobile, and EE as an example, use the same implantation. AT&T USA's implantation is not compatible with T-Mobile's, which makes it harder to use a non-AT&T device on their network. Asia has a more proprietary implementation that is focused towards the market those devices are made for and designed to work in. If they were to use the stock Android implementation that T-Mobile uses, VoLTE, VoNR, and WiFi calling would not work on Asian carriers.

There are tutorials out there including on the official Xiaomi boards on how to alter the carrier profile using root. The issue with that is, that the profile resets to what it originally was every time the device is rebooted or updated. Qualcomm's QPST is the only way to properly set this, but it is not a user friendly tool and can easily brick your device or cause it to no longer be able to connect to any networks. The way the tool works is by writing to the oartition of the device where the modem firmware and configuration is stored, which is outside of the OS. If this gets messed uo, a factory reset will not restore it! This is why I don't talk about it much.

I used a Motorola phone I bought in the US for 4 years in India, so is the interregional implementation incompatibility only one-way? Phones from the US will work universally but not the other way around? You also say that Asia's proprietary implementation, if configurable to the stock android implementation necessary for US networks, would no longer work on Asian carriers, but that goes back to my question of how do phones from the US work fine abroad? Also how does international roaming work then if network configuration is device specific?

The 3 main US carriers all use different implementations. US devices adapt to the carrier SIM put in the device to be as compatible as possible. Then you add in Canadian and Mexican roaming as well as people traveling a lot between the 3 countries in North America, which makes US devices very carrier friendly, even outside of of North America. Asian devices makes can add more North American compatibility to their Android versions but they don't.

India devices are also very versatile because of the sheer amount of regional carriers that all have very different deployments. I have personally rum the India firmware on my OnePlus 7 Pro and OnePlus 8T and had no issues connecting to T-Mobile and Canadian carriers.

So when you say run firmware, you mean flashing rom right? Or is it qpst? So have you really not had any experience or heard of success stories of cn devices, particularly mediatek, of being configurable to North American networks? Do you think it would make a difference if I flashed a global rom onto my note 13 pro +? Or is there something more, like a qpst variant for mediatek devices that id have to contact a xiaomi service person to support me with?

US firmware is setup to work with all of the US carriers. There are carrier variant firmware but those will still work with other carriers for the most part. Asian firmware, even using global ROM's, is still geared towards Asia and not countries where those devices are not officially sold. QPST is what is needed to change the carrier profile on Xiaomi devices.