Database Users

Help with 935 variants please

I've been combing the forums and I'm still unclear on a few things and looking for help. Current AT&T customer and I plan to switch to T-Mobile soon. Any confirmation or corrections/answers to the questions/statements below would be really appreciated.
1. The 935F variant is the international model that works with all GSM carriers (and I assume without any carrier bloatware) but VoLTE and wifi calling will not work on any GSM carrier here in the US. Theres a secondary 935F model (d?)- whats the advantage there? Shopping tools that let you compare the models show no difference but always priced differently. There is something I'm missing.
2. The 935U variant is official US unlocked model for use with any carrier. Only silver. I have not seen any posts confirming that VoLTE and wifi calling works- and will continue to work if you switch carriers.
3. Lots of listings for factory unlocked 935A variants. Official AT&T version. That just means a reseller has applied unlock codes to each and resells them? I'm very unclear here. Listings always say compatible with all GSM carriers. But will AT&T bloatware, logo continue to survive? And again, will VoLTE and wifi calling work and continue to work if I switch carriers. This is also the cheapest phone to buy virtually new. But if truly GSM compatible with features that are important to me are intact among carriers- what would I get for the significant premium to get the 935U? Besides, I wanted black.
4. Black Pearl- has this been released in the US and in any specific model? I have not seen one.
Thanks in advance. Really appreciate it.

FD is dual sim. You can put 2 GSM simcards there and both are active. Can send and receive sms or calls.
Sent from my Galaxy S7 Edge Duos via Tapatalk

You can install 935U stock firmware on att/tmobile/verizon version. If used on tmobile network, you will get wifi call and volte. For att you have to install or have att stock.

xometer10 said:
I've been combing the forums and I'm still unclear on a few things and looking for help. Current AT&T customer and I plan to switch to T-Mobile soon. Any confirmation or corrections/answers to the questions/statements below would be really appreciated.
1. The 935F variant is the international model that works with all GSM carriers (and I assume without any carrier bloatware) but VoLTE and wifi calling will not work on any GSM carrier here in the US. Theres a secondary 935F model (d?)- whats the advantage there? Shopping tools that let you compare the models show no difference but always priced differently. There is something I'm missing.
2. The 935U variant is official US unlocked model for use with any carrier. Only silver. I have not seen any posts confirming that VoLTE and wifi calling works- and will continue to work if you switch carriers.
3. Lots of listings for factory unlocked 935A variants. Official AT&T version. That just means a reseller has applied unlock codes to each and resells them? I'm very unclear here. Listings always say compatible with all GSM carriers. But will AT&T bloatware, logo continue to survive? And again, will VoLTE and wifi calling work and continue to work if I switch carriers. This is also the cheapest phone to buy virtually new. But if truly GSM compatible with features that are important to me are intact among carriers- what would I get for the significant premium to get the 935U? Besides, I wanted black.
4. Black Pearl- has this been released in the US and in any specific model? I have not seen one.
Thanks in advance. Really appreciate it.
Click to expand...
Click to collapse
1. 935F is the European / International model. 935FD, D stands for Dual-SIM, both slots will be able to accept a GSM SIM card and are usually used, as one for work, and one as a personal number. Dual-SIM however, is not a popular concept in the US.
2. Check the 935U threads, if a CSC flash is possible, it might work. Though, I'm not sure.
3. Yes, if you have an AT&T phone, it'll still have the AT&T ROM, which will always remain the same, regardless. It will work with other carriers, meaning SMS, Data and calls are compatible, but things like VoLTE and WiFi calling might not work on the carrier that the phone isn't intended for.
4. No it hasn't. It's been released in South Korea with 128GB of internal storage. Also available in the UAE, India and some other Middle Eastern countries. Only in a Dual SIM Configuration (SM-G935FD), and with 128GB of internal storage. It's a limited edition phone, and not sure if it'll be launched in the US.

hp79 said:
You can install 935U stock firmware on att/tmobile/verizon version. If used on tmobile network, you will get wifi call and volte. For att you have to install or have att stock.
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Click to collapse
A couple of followups if thats ok:
1. So if I purchase a "factory unlocked" 935A, before I insert any SIM, I can immediately flash the 935U firmware and it will remain unlocked? I couldn't find a single post that said VoLTE or Wifi calling worked with the 935U firmware on T-mobile (AT&T- what do you have to install?)
2. Flashing to firmware is not considered rooting the device? My work will not let my device connect to the network if it is rooted.
Seems like there is no reason to spend the extra money for the 935U variant. I can save hundreds and purchase an unlocked 935A and flash the firmware. I've rooted devices before and the process looks similar.
Thanks.

xometer10 said:
A couple of followups if thats ok:
1. So if I purchase a "factory unlocked" 935A, before I insert any SIM, I can immediately flash the 935U firmware and it will remain unlocked? I couldn't find a single post that said VoLTE or Wifi calling worked with the 935U firmware on T-mobile (AT&T- what do you have to install?)
2. Flashing to firmware is not considered rooting the device? My work will not let my device connect to the network if it is rooted.
Seems like there is no reason to spend the extra money for the 935U variant. I can save hundreds and purchase an unlocked 935A and flash the firmware. I've rooted devices before and the process looks similar.
Thanks.
Click to expand...
Click to collapse
According to other people in verizon 935u thread and att 935u thread, volte and wifi call works on tmobile. For att wifi call and volte, it must be a ATT carrier firmware. ATT only let their branded phones have wifi call and volte while tmobile allows any phone to do this. That's why with 935U wifi call and volte will work fine on tmobile.
Every time you insert a new sim the phone will adjust settings, so there's no relation with what you can install.
Flashing is done through Odin while phone is in Download mode. There no root involved.

SM-G950F on T-Mobile US - CSC, WiFi Calling, VoLTE, 256QAM, 4x4 MIMO?

I am considering upgrading to the S8. I like that the G950F has an unlocked bootloader on a phone that has (almost) everything I want.
But it seems like it's a bit of a hassle to get it to work fully on the T-Mobile network. It looks like I can flash the CSC to enable WiFi Calling and VoLTE on it, but is there any hope for 256QAM and 4x4 MIMO? There's hardly any information about this other than one or two threads. So I'd like to know:
If I go with the G950F over the T-Mobile or Unlocked US variants, what am I missing out on out of the box?
What will flashing the T-Mobile CSC not fix? (I currently think it does fix WiFi Calling and VoLTE.)
Can I flash the T-Mobile US modem on the G950F to fix this, or will that just brick my device? (Snapdragon image on Exynos terrifies me.)
Am I missing some other way (like a secret service mode or something) that would allow me to force 256QAM and/or 4x4 MIMO on the G950F?
I really hate that I can't just have a US model with an unlocked bootloader...

I think Galaxy S8 International variant maybe missing some bands and I would suggest you either get T-Mobile as you mentioned or US unlocked. With US unlocked which I already ordered from Samsung, should support all T-Mobile features: VoLTE, Band 12 and WiFi Calling. At the moment Samsung offers $200 off if you trade in any Android or iOS device. Just check their page for Trade-in details.

Charkatak said:
I think Galaxy S8 International variant maybe missing some bands and I would suggest you either get T-Mobile as you mentioned or US unlocked. With US unlocked which I already ordered from Samsung, should support all T-Mobile features: VoLTE, Band 12 and WiFi Calling. At the moment Samsung offers $200 off if you trade in any Android or iOS device. Just check their page for Trade-in details.
Click to expand...
Click to collapse
Can I trade any device?
I got a one plus one somewhere.

borisb said:
Can I trade any device?
I got a one plus one somewhere.
Click to expand...
Click to collapse
I don't see why you can't. It said any Android/iOS device, but just has to be in good condition. Check it out: http://www.samsung.com/us/trade-in/terms-and-conditions/

I'm using an international S8 on Tmobile, works fine. I'm in the middle of nowhere and it actually gets better signal than a Tmobile Pixel and S6 Edge I had before.

sketron13 said:
I'm using an international S8 on Tmobile, works fine. I'm in the middle of nowhere and it actually gets better signal than a Tmobile Pixel and S6 Edge I had before.
Click to expand...
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Does you phone show 4G or 4G LTE?

It has 4G LTE shown

sketron13 said:
It has 4G LTE shown
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Click to collapse
Hmm, I don't remember which bands exactly and how many, but F model had some bands missing for T-Mobile.

Just one night frequency

The exynos variant lacks 4x4 mimo and 256qam from what I've read. It achieves 1gb down via 5xCA. But also only allows it to max upload at 150mb/s
So it would only be able to utilize the 3xCA from tmobile. And not get max possible downloads. But the F does support all 3 of t-mobile's used bands

Acoustichayes said:
The exynos variant lacks 4x4 mimo and 256qam from what I've read. It achieves 1gb down via 5xCA. But also only allows it to max upload at 150mb/s
So it would only be able to utilize the 3xCA from tmobile. And not get max possible downloads. But the F does support all 3 of t-mobile's used bands
Click to expand...
Click to collapse
Got it. That's what I was looking for, thanks. My understanding is that it's a hardware issue that can't easily be fixed via service mode or flashing something, but it doesn't look like I'd miss out on much overall.
I am in a 4x4 MIMO service area though so maybe I'll just hold out for now and see what happens over the next few weeks/months.

Can someone point me to the thread for how to make a sm-g950f have volte and wifi calling on T-Mobile?
My searches turned up nothing concrete if this is possible but I found a Note 8 thread that sounded promising.

Does anyone know if I were to flash the latest Germany T-Mobile firmware (DTM) from Sammobile, would that enable VoLTE, WiFi Calling here in the US?
Currently my G950F S8 has the Australian (XSA) firmware installed and it doesn't have VoLTE or WiFi Calling. The WiFi Calling setting in Quicktiles is greyed out.

Is SM-G9750/DS (China/Hong Kong version) compatible with AT&T and T-Mobile

I want to buy SM-G9750/DS (Dual SIM). This is Chinese Version (sourced from Hong Kong).
It has Snapdragon processor.
Is this version compatible AT&T and T-Mobile?

lahcim2000 said:
I want to buy SM-G9750/DS (Dual SIM). This is Chinese Version (sourced from Hong Kong).
It has Snapdragon processor.
Is this version compatible AT&T and T-Mobile?
Click to expand...
Click to collapse
It looks like its missing some LTE bands compared to the US version.

Usually don't have band 71 for TMobile... At least on Note 9.

galaxys said:
Usually don't have band 71 for TMobile... At least on Note 9.
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Click to collapse
Can I somehow enable those bands?
Both phones look to be running same Qualcomm chipset.

lahcim2000 said:
Can I somehow enable those bands?
Both phones look to be running same Qualcomm chipset.
Click to expand...
Click to collapse
Unfortunately No!

galaxys said:
Unfortunately No!
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Click to collapse
What about CDMATool?
I see it can enable bands, but I do not see option for band 66 or 71 in a tool.
Thoughts?

I have a note 9 from the same source, perfect expect those carrier specific feartue such as volte, wifi calling . It does work with LTE, but almost half of speed of what I can get from a us version.

lahcim2000 said:
I want to buy SM-G9750/DS (Dual SIM). This is Chinese Version (sourced from Hong Kong).
It has Snapdragon processor.
Is this version compatible AT&T and T-Mobile?
Click to expand...
Click to collapse
The S9 Plus, SM-G9650 (Hong Kong) is compatible with AT&T and T-Mobile, I'd be surprised to learn an SM-G9750 isn't. It should work on all CDMA Networks. In some instances sellers on Ebay and Amazon will state that particular variant isn't compatible when in fact it is, just to cover their rear ends.

my sprint sim isnt working for my 9750 out the box... i figured they couldnt do anything, but i called anyways, the sprint rep said if it were "unlocked" it would work, maybe its a network or regional lock, i dont know. Im trying everything to get it "unlocked"... if thats even the problem. Currently waiting on a paid sim unlock service to get back with me, see if they can help.
Any one get a HK s9 or s10 to work on sprint?

If it's Exynos it's not going to work on Sprint or Verizon.
My Exynos S9+ and Note9 work fine with TMO.

monroe0328 said:
my sprint sim isnt working for my 9750 out the box... i figured they couldnt do anything, but i called anyways, the sprint rep said if it were "unlocked" it would work, maybe its a network or regional lock, i dont know. Im trying everything to get it "unlocked"... if thats even the problem. Currently waiting on a paid sim unlock service to get back with me, see if they can help.
Any one get a HK s9 or s10 to work on sprint?
Click to expand...
Click to collapse
The s10 9750 is compatible for flashing HK roms, try flashing HK rom for your 9750 instead.

Please Help
oscarxvita said:
The s10 9750 is compatible for flashing HK roms, try flashing HK rom for your 9750 instead.
Click to expand...
Click to collapse
how to u flash a rom on the SM-G9750... i googled but getting a lot of wrong forums

Region Locket
is this hong-kong version (G9750) region locket ? if yes how to unlock ?

lahcim2000 said:
I want to buy SM-G9750/DS (Dual SIM). This is Chinese Version (sourced from Hong Kong).
It has Snapdragon processor.
Is this version compatible AT&T and T-Mobile?
Click to expand...
Click to collapse
hello everyone
I have question.... please tell me Is SM-G9750/DS with snapdragon (China/Hong Kong version with TGY csc) compatible with AT&T and T-Mobile.
I want to know, it will work Wificalling & Volte on T-mobile ?
someone has this one smartphone and uses it in the USA ?
Thank you

S10 Plus G9750 Chinese to Global ROM

Hi! I just recieved my G9750 Snapdragon 855 S10 Plus, which turned out to be a chinese one. Is it any way to install any non-chinese/global ROM onto it? Like a USA ROM, which is also a Snapdragon one? I live in the UK, but I wanted one with the Snapdragon chipset. Thanks for any help.

Also in the same situation

Ditto - imported to UK.

danikollar said:
Hi! I just recieved my G9750 Snapdragon 855 S10 Plus, which turned out to be a chinese one. Is it any way to install any non-chinese/global ROM onto it? Like a USA ROM, which is also a Snapdragon one? I live in the UK, but I wanted one with the Snapdragon chipset. Thanks for any help.
Click to expand...
Click to collapse
What do you mean by "which turned out to be a Chinese one"? Can't you set it to English? I have the G-9750 and everything is English.

lexi250 said:
What do you mean by "which turned out to be a Chinese one"? Can't you set it to English? I have the G-9750 and everything is English.
Click to expand...
Click to collapse
Of course it's include all languages, english also, but G9750 is for the Chinese market, so as the ROM is chinese. For example the Samsung Pay is Hong Kong specific one, with promotions from there. Etc....

So you wanted the G-9750 for the dual SIM functionality? I'm using the G-9750 in Canada, and Samsung Pay works. Did you try registering your CC?

All the S10's are dual SIM. I wanted the Snapdragon 855 version, cause it has better battery life compared to the Exynos version. I know that for sure, cause I had one at launch. And almost full support for the GCAM.

danikollar said:
All the S10's are dual SIM. I wanted the Snapdragon 855 version, cause it has better battery life compared to the Exynos version. I know that for sure, cause I had one at launch. And almost full support for the GCAM.
Click to expand...
Click to collapse
Yes Snapdragon has better battery life for screen on runtime. There is no international ROM for Chinese variant. You have to use the Hong Kong firmware by changing language to English. Samsung Pay works as well, just different ads from Hong Kong when you use it.

VICosPhi said:
Yes Snapdragon has better battery life for screen on runtime. There is no international ROM for Chinese variant. You have to use the Hong Kong firmware by changing language to English. Samsung Pay works as well, just different ads from Hong Kong when you use it.
Click to expand...
Click to collapse
And no not all S10's are dual sim.

Iain_S said:
And no not all S10's are dual sim.
Click to expand...
Click to collapse
Correct, can't believe Samsung didn't follow Apple's suit here
Sent from my SM-G975F using Tapatalk

Iain_S said:
And no not all S10's are dual sim.
Click to expand...
Click to collapse
My UK 512GB S10+ Plus was!

danikollar said:
My UK 512GB S10+ Plus was!
Click to expand...
Click to collapse
Yes UK has all dual SIM models. US and Canada does not
Sent from my SM-G975F using Tapatalk

Yeah to be honest after a day with the phone - the only thing that makes it feel Chinese/HK is Samsung Pay... and I'm not entirely sure i'll be using it over GPay.
Looks like we have an unlocked bootloader though so will personally its just a matter of time until I brick my phone

lexi250 said:
What do you mean by "which turned out to be a Chinese one"? Can't you set it to English? I have the G-9750 and everything is English.
Click to expand...
Click to collapse
ssjgesus said:
Yeah to be honest after a day with the phone - the only thing that makes it feel Chinese/HK is Samsung Pay... and I'm not entirely sure i'll be using it over GPay.
Looks like we have an unlocked bootloader though so will personally its just a matter of time until I brick my phone
Click to expand...
Click to collapse
How did you find out it has an unlocked bootloader? The Snapdragon ones should be with the locked bootloader.

danikollar said:
How did you find out it has an unlocked bootloader? The Snapdragon ones should be with the locked bootloader.
Click to expand...
Click to collapse
The Chinese Smapdragon devices have an unlocked bootloader.

lexi250 said:
So you wanted the G-9750 for the dual SIM functionality? I'm using the G-9750 in Canada, and Samsung Pay works. Did you try registering your CC?
Click to expand...
Click to collapse
Hi, if I may ask that have you linked your Canadian cards to the G9750 and it works with Samsung Pay? I am planning to buy one but the Samsung Pay is very important to me...

adding to the same question , i have a HongKong variant (SM-G9750) with Unlocked bootloader (u get the option to unlock in developer mode) , i m using it in india with Jio & Vodafone (network providers).. when i was on roaming i saw my phone not picking up network that well compared to my friends on the same network diff phones. i guess thats coz their CSC is Indian and mine is Hong kong ( i can be wrong in this , correct if i am) in that case is there a way to flash Indian CSC or Multi CSC on my device.

hi everybody , i have s10 plus hong kong, it has a problem with battery, cell standby higher than 15% on mobile network 4g and 3g, is there any way to solve this problem ? while s10 5g cell standby only has 1%

v1k1ngc0d3 said:
adding to the same question , i have a HongKong variant (SM-G9750) with Unlocked bootloader (u get the option to unlock in developer mode) , i m using it in india with Jio & Vodafone (network providers).. when i was on roaming i saw my phone not picking up network that well compared to my friends on the same network diff phones. i guess thats coz their CSC is Indian and mine is Hong kong ( i can be wrong in this , correct if i am) in that case is there a way to flash Indian CSC or Multi CSC on my device.
Click to expand...
Click to collapse
I'm also waiting for this... as i need auto call recording feature too..
Sent from my SM-G9750 using Tapatalk

Just adding to the discussion here....I'm living in mainland China, not Hong Kong, and am using a Chinese sim card in my S7 that i brought with me from North America. It works fine with the apps i had installed when I came over. This includes VPN services, the Google play store and all its goodies. I just purchased the S10+ G9750 here in mainland China (not in Hong Kong). I don't have it in my hand yet, but when I get it I expect it to be full of Chinese software and restricting type soft/bloatware that could potentially limit both my access to VPN and the Google play store (FWIW, i have heard many expats here who have bought local xiaomi's and huawei's and have tried to put a VPN on them on to have it magically disappear from their phones a few days/weeks afterwards...I assume there is some sort of setting or software that does this as VPN services are not "legal" in China. I have also heard of people having problems with certain western APKs when installing them on these same Chinese phones).
That said...I have a few questions....hopefully this is the correct place to ask them...
1) Is there a difference between a Hong Kong G9750 and a mainland China one?
2) Based on what I have read, my G9750 does have an unlockable bootloader....if so...
3) what am i able to do with an unlockable bootloader? It seems that people interchangeably use "rooting" and bootloading a new rom on to an international phone so i'm confused af. Flashing the firmware???
Ultimately, i would like to completely wash this Chinese phone of any potential BS Chinese software and install a western ROM (i.e., Canada or US) that will still make it work in China, but will still offer me all the Google play store and other western app functionality as I have currently with my s7.
Thoughts?

Questions Re: International (or Latin) unlocked S10+ or Note10+ / T-Mobile

So I am looking to buy an international (or Latin) version of either the S10+ or the Note 10+.
I am on T-Mobile in the U.S.
1. How "bad" will it be if the phone has 3 out of T-Mobile's main bands? It only lacks 71, so what's the impact will be if I don't have band 71 on this phone with T-Mobile?
2. I read in the forum about flashing T-Mobile firmware on unlocked phones. How necessary is it? I prefer not to mess with flashing anything; done it in the past, I am not 'afraid' of it, but I just don't feel like going that route. Will I be missing anything from the T-Mobile network and services if I keep the phone in its stock ROM?
For example: Wifi Calling (important to me), VoLTE, etc. Will I have access to these features if I don't flash the carrier's firmware?
Thank you.

Band 71 is used only in rural areas where cell towers are very far apart . My phones have never used band 71. If you don't know what bands your phone typically is using you can download a free signal app from the Play Store that will show what band your phone is connected to. Unless you live in a very rural area or frequently find yourself in rural areas it's unlikely you need band 71.
Flashing T-Mobile firmware shouldn't be necessary. I don't have the international S10+ but rather the US unlocked model and I get both WiFi Calling and Volte fine without T-Mobile firmware.
I've used many different models of international unlocked phones from Xiaomi and Huawei on T-Mobile and always got both WiFi Calling and Volte to work with only one exception--the Mate 20 Pro. I had to get rid of that phone even though I really liked it because calls kept going to voicemail without the phone ever ringing first.
It turns out that on T-Mobile if your phone supports band 12 it also needs to support Volte or calls go straight to voicemail without ringing if the caller is using Volte . I never had that problem previously because in 5 years of using international unlocked phones the M20P was the first where Volte didn't work on T-Mobile.
There were lots of posts from T-Mobile customers in the XDA M20P threads about calls going straight to voicemail. I haven't read a single post about that issue with the S10+ so it's pretty safe to assume that the international S10+ works fine with Volte on T-Mobile.
Until the S8 Samsung didn't even sell a US unlocked model--everyone in the US with unlocked Samsung phones were using the international models with the Exynos chip and those phones always worked perfectly with T-Mobile which is very BYOP friendly (unlike AT&T).
The only thing you would be missing on the vanilla Samsung firmware is Visual Voicemail but last I checked you could just download the official T-Mobile Visual Voicemail app from the Play Store.
You would also receive your OTA updates from Samsung rather than T-Mobile but that's actually a plus because the unlocked Exynos models receive updates much more quickly than all of the US models including the unlocked Snapdragon models.
Sorry for the very long answer but I wanted to be thorough.
You should be fine with an international unlocked S10+ on T-Mobile. This is a much better phone than unlocked models from Google Pixel and One Plus so I would recommend going for it.
No manual flashing on your part will be necessary.

@jhs39 - Thank you for your extensive response. It is greatly appreciated!
OK, so I mostly use Band 4 with my current phone, which is one of TMB's main bands, so it seems like that indeed the lack of 71 won't be an issue.
However, how do I know if the Int. version will support VoLTE on the TMB network? I can't see anywhere any information about this phone even supports VoLTE (other than the carrier's model of course).
What about Video Calling?
Thanks again.

sbi1 said:
@jhs39 - Thank you for your extensive response. It is greatly appreciated!
OK, so I mostly use Band 4 with my current phone, which is one of TMB's main bands, so it seems like that indeed the lack of 71 won't be an issue.
However, how do I know if the Int. version will support VoLTE on the TMB network? I can't see anywhere any information about this phone even supports VoLTE (other than the carrier's model of course).
What about Video Calling?
Thanks again.
Click to expand...
Click to collapse
If the international model didn't support Volte on T-Mobile there would be posts on XDA complaining about calls going straight to voicemail without the phone ringing. There were multiple threads about that issue in the M20P section but I haven't seen a single complaint about that happening with the S10+.
This phone has been out since early Spring so if there was a problem using the international model with T-Mobile somebody would have reported it by now.
I don’t know anything about video calling though because I use T-Mobile's network via an MVNO and my carrier doesn't offer video calling.

jhs39 said:
Band 71 is used only in rural areas where cell towers are very far apart . My phones have never used band 71. If you don't know what bands your phone typically is using you can download a free signal app from the Play Store that will show what band your phone is connected to. Unless you live in a very rural area or frequently find yourself in rural areas it's unlikely you need band 71.
Flashing T-Mobile firmware shouldn't be necessary. I don't have the international S10+ but rather the US unlocked model and I get both WiFi Calling and Volte fine without T-Mobile firmware.
I've used many different models of international unlocked phones from Xiaomi and Huawei on T-Mobile and always got both WiFi Calling and Volte to work with only one exception--the Mate 20 Pro. I had to get rid of that phone even though I really liked it because calls kept going to voicemail without the phone ever ringing first.
It turns out that on T-Mobile if your phone supports band 12 it also needs to support Volte or calls go straight to voicemail without ringing if the caller is using Volte . I never had that problem previously because in 5 years of using international unlocked phones the M20P was the first where Volte didn't work on T-Mobile.
There were lots of posts from T-Mobile customers in the XDA M20P threads about calls going straight to voicemail. I haven't read a single post about that issue with the S10+ so it's pretty safe to assume that the international S10+ works fine with Volte on T-Mobile.
Until the S8 Samsung didn't even sell a US unlocked model--everyone in the US with unlocked Samsung phones were using the international models with the Exynos chip and those phones always worked perfectly with T-Mobile which is very BYOP friendly (unlike AT&T).
The only thing you would be missing on the vanilla Samsung firmware is Visual Voicemail but last I checked you could just download the official T-Mobile Visual Voicemail app from the Play Store.
You would also receive your OTA updates from Samsung rather than T-Mobile but that's actually a plus because the unlocked Exynos models receive updates much more quickly than all of the US models including the unlocked Snapdragon models.
Sorry for the very long answer but I wanted to be thorough.
You should be fine with an international unlocked S10+ on T-Mobile. This is a much better phone than unlocked models from Google Pixel and One Plus so I would recommend going for it.
No manual flashing on your part will be necessary.
Click to expand...
Click to collapse
That's odd. I'm using a mate 20X and the although it lacks bands 66 and 71 I don't get calls going to voicemail. In fact when viewing my historical phone signal via gsam app, it shows that I always receive a better signal than even the S10+ that I'm currently using. Both devices on T-Mobile USA.
Sent from my SM-G975U using Tapatalk

sbi1 said:
So I am looking to buy an international (or Latin) version of either the S10+ or the Note 10+.
I am on T-Mobile in the U.S.
1. How "bad" will it be if the phone has 3 out of T-Mobile's main bands? It only lacks 71, so what's the impact will be if I don't have band 71 on this phone with T-Mobile?
2. I read in the forum about flashing T-Mobile firmware on unlocked phones. How necessary is it? I prefer not to mess with flashing anything; done it in the past, I am not 'afraid' of it, but I just don't feel like going that route. Will I be missing anything from the T-Mobile network and services if I keep the phone in its stock ROM?
For example: Wifi Calling (important to me), VoLTE, etc. Will I have access to these features if I don't flash the carrier's firmware?
Thank you.[/QUOTE
I have the Hong Kong variant SM-G975 with T-Mobile. No issues with bands, VoLTE. Wifi Calling or 4G, no impact. You won't need to flash the device.
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varcor said:
I have the Hong Kong variant SM-G975 with T-Mobile. No issues with bands, VoLTE. Wifi Calling or 4G, no impact. You won't need to flash the device.
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Thanks @varcor . What about Video calling?
BTW - is it 975F or something else?

I use Skype for Video Calling, it works fine. Mine is an SM-G9750, the best price I've seen is on Ebay. The only issue is when you first get the device you'll need to change the language since it's setup in Mandarin. A bit challenging but not a big deal. The Ebay vendor is in Houston which is where the device ships from, only takes a few days.
https://www.ebay.com/itm/Samsung-Ga...im-FACTORY-UNLOCKED-6-4-8GB-RAM-/192846270776

varcor said:
I use Skype for Video Calling, it works fine. Mine is an SM-G9750, the best I've seen is on Ebay. The only issue is when you first get the device you'll need to change the language since it's setup in Mandarin. A bit challenging but not a big deal. The Ebay vendor is in Houston which is where the device ships from, only takes a few days.
https://www.ebay.com/itm/Samsung-Ga...im-FACTORY-UNLOCKED-6-4-8GB-RAM-/192846270776
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Oh yeah, the legendary Never MSRP.
Sent from my SM-G975U using Tapatalk

Yep, I've bought a number of devices from them, won't use anyone else. Lowest prices, great customer service as well.

varcor said:
I use Skype for Video Calling, it works fine. Mine is an SM-G9750, the best price I've seen is on Ebay. The only issue is when you first get the device you'll need to change the language since it's setup in Mandarin. A bit challenging but not a big deal. The Ebay vendor is in Houston which is where the device ships from, only takes a few days.
https://www.ebay.com/itm/Samsung-Ga...im-FACTORY-UNLOCKED-6-4-8GB-RAM-/192846270776
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I must the F model. I travel to Israel with a local SIM and they use the F model, and it's the only possibility I have to use their WiFi calling while there. I am not 100% sure it'll work because of firmware but better chances with F model.
Thanks.

Limeybastard said:
That's odd. I'm using a mate 20X and the although it lacks bands 66 and 71 I don't get calls going to voicemail. In fact when viewing my historical phone signal via gsam app, it shows that I always receive a better signal than even the S10+ that I'm currently using. Both devices on T-Mobile USA.
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Not having bands 66 & 71 don't cause the problem with T-Mobile calls going straight to voicemail--if band 12 is supported on a phone T-Mobile assumes the phone also supports Volte and if it doesn't then you get calls going straight to voicemail.
I'm not familiar with the Mate 20X but before the M20P I had a P20 Pro, Mate 10 Pro and P10 Pro and none of those phones had an issue because T-Mobile Volte worked with all of them.
It's also possible the problem with the P20 Pro was fixed after I got rid of the phone since it was a firmware issue that was fixable in a software update . I kept mine for 6 months before throwing in the towel. The only workaround was to turn off 4G in the network settings. With 4G off you would receive all calls since Volte is a 4G function.
I personally love Huawei phones. Hopefully after Trump is gone all of the nonsense with Huawei being barred from using Google apps and bullied out of the US market will go away but they might decide selling their products here isn't worth the aggravation.
I've also used a bunch of unlocked Xiaomi phones on T-Mobile with no issues. A nice feature in MIUI is that if Volte doesn't work out of the box there's a dial code you can enter to manually enable it.
Band 66 is an offload for band 4 when band 4 traffic is high but if a phone doesn't have band 66 it just stays on 4 so not having 66 on an unlocked phone has never caused any problems for me.
Band 71 is only live in parts of the country and is relatively new. It can transmit a signal over unusually long distances and is used to provide cell coverage in rural areas where it would cost too much to build a full network of cell towers.

jhs39 said:
Not having bands 66 & 71 don't cause the problem with T-Mobile calls going straight to voicemail--if band 12 is supported on a phone T-Mobile assumes the phone also supports Volte and if it doesn't then you get calls going straight to voicemail.
I'm not familiar with the Mate 20X but before the M20P I had a P20 Pro, Mate 10 Pro and P10 Pro and none of those phones had an issue because T-Mobile Volte worked with all of them.
It's also possible the problem with the P20 Pro was fixed after I got rid of the phone since it was a firmware issue that was fixable in a software update . I kept mine for 6 months before throwing in the towel. The only workaround was to turn off 4G in the network settings. With 4G off you would receive all calls since Volte is a 4G function.
I personally love Huawei phones. Hopefully after Trump is gone all of the nonsense with Huawei being barred from using Google apps and bullied out of the US market will go away but they might decide selling their products here isn't worth the aggravation.
I've also used a bunch of unlocked Xiaomi phones on T-Mobile with no issues. A nice feature in MIUI is that if Volte doesn't work out of the box there's a dial code you can enter to manually enable it.
Band 66 is an offload for band 4 when band 4 traffic is high but if a phone doesn't have band 66 it just stays on 4 so not having 66 on an unlocked phone has never caused any problems for me.
Band 71 is only live in parts of the country and is relatively new. It can transmit a signal over unusually long distances and is used to provide cell coverage in rural areas where it would cost too much to build a full network of cell towers.
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P20 pro was certified and worked fully on T-Mobile , most devices after that were not.
I don't think my mate 20x connected to band 12, but if it did, then yes it'll probably go straight to voicemail.
Sent from my SM-G975U using Tapatalk

sbi1 said:
I must the F model. I travel to Israel with a local SIM and they use the F model, and it's the only possibility I have to use their WiFi calling while there. I am not 100% sure it'll work because of firmware but better chances with F model.
Thanks.
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The SM-G975F is the Exynos SoC variant for Europe. The SM-G9750 has the Snapdragon SoC and dual SIM's as well. Wifi Calling will work on both devices in any region, including Israel as long as the service provider offers it. The only thing I would recommend is you do some research on Exynos vs Snapdragon SoC's in the S10. Good luck!

varcor said:
The SM-G975F is the Exynos SoC variant for Europe. The SM-G9750 has the Snapdragon SoC and dual SIM's as well. Wifi Calling will work on both devices in any region, including Israel as long as the service provider offers it. The only thing I would recommend is you do some research on Exynos vs Snapdragon SoC's in the S10. Good luck!
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I am aware of the differences between the two chips.
In regards to WiFi Calling - I am a bit skeptical. This provider does have WiFi calling services, however they have a list of devices that are supported. Clearly they list devices and firmwares that they sell, not BYOD phones, and they sell the F version. I currently use ZTE Axon 7, I have WiFi calling on T-Mobile but it does not work on the Israeli network and when I try to 'register' it for this service through their app, it clearly says that the device is not supported.
That being said - I can't tell you if my phone doesn't work on their WF calling because it's not even sold in Israel. It could very well be that any version of Galaxy S10+ will be supported regardless of firmware. simply because it is sold there. Clearly there is no way to know this beforehand. I asked them, they of course can only guarantee phones that are sold by them and are on the list.
BTW - the Israeli version of the 975F is single SIM, they don't have the D/S, although I can't imagine this should have any impact of phone supporting or not supporting WF calling.
What's the difference between the F and the O, other than the region they are sold in?
Thanks.

Limeybastard said:
P20 pro was certified and worked fully on T-Mobile , most devices after that were not.
I don't think my mate 20x connected to band 12, but if it did, then yes it'll probably go straight to voicemail.
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Devices don't need to be certified by T-Mobile to work with Volte. All of my recent Xiaomi phones worked with Volte--none of the models were officially sold in the US or certified by T-Mobile. The P20 Pro was not sold in the US so there was zero reason for it to be certified by T-Mobile. The last Huawei phone officially sold here was the Mate 10 Pro. AT&T and Verizon require that devices be certified by them to work with Volte on their networks but T-Mobile does not. T-Mobile is very BYOP friendly.

jhs39 said:
Devices don't need to be certified by T-Mobile to work with Volte. All of my recent Xiaomi phones worked with Volte--none of the models were officially sold in the US or certified by T-Mobile. The P20 Pro was not sold in the US so there was zero reason for it to be certified by T-Mobile. The last Huawei phone officially sold here was the Mate 10 Pro. AT&T and Verizon require that devices be certified by them to work with Volte on their networks but T-Mobile does not. T-Mobile is very BYOP friendly.
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Thanks for the clarification. So why is it then that same device , but using different sim card would show the Volte toggle or hide it from the user menu? Example, mate 20 does have Volte capabilities yet its missing the Volte toggle switch. I know on the Xioami devices one can enter a #*code to force it show that option. I think what makes it even more convulsing is that Huawei global versions have various region firmware via their Cust codes. Each one I noticed behaves slighly different using same T-Mobile SIM card. Cheers
You mentioned all calls went to VM on up 20pro, why do you think that was the case, you mentioned earlier that you thought possibly it may have been firmware related amongst other things.
Sent from my SM-G975U using Tapatalk

sbi1 said:
I am aware of the differences between the two chips.
In regards to WiFi Calling - I am a bit skeptical. This provider does have WiFi calling services, however they have a list of devices that are supported. Clearly they list devices and firmwares that they sell, not BYOD phones, and they sell the F version. I currently use ZTE Axon 7, I have WiFi calling on T-Mobile but it does not work on the Israeli network and when I try to 'register' it for this service through their app, it clearly says that the device is not supported.
That being said - I can't tell you if my phone doesn't work on their WF calling because it's not even sold in Israel. It could very well be that any version of Galaxy S10+ will be supported regardless of firmware. simply because it is sold there. Clearly there is no way to know this beforehand. I asked them, they of course can only guarantee phones that are sold by them and are on the list.
BTW - the Israeli version of the 975F is single SIM, they don't have the D/S, although I can't imagine this should have any impact of phone supporting or not supporting WF calling.
What's the difference between the F and the O, other than the region they are sold in?
Thanks.
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You're correct regarding Single SIM for the SM-G975F, the Dual SIM option is available in the SM-G975F/DS. I personally wouldn't consider obtaining a device in Israel if the majority of the time I'm the US. The major differences are SoC's, a minor difference in CPU Clock Speed and Cores. The SM-G975F has no FM Radio and offers fewer Primary Network capabilities. You can view a back-to-back comparison here.
https://www.phonemore.com/compare/p...gb-vs-galaxy-s10-plus-sm-g9750-128gb/10134260
This is quite different than your original question but with that being stated I would be confident enough in the SM-G9750's compatibility with the Israeli network for Wifi Calling. The worst case is not having Wifi Calling in Israel, which isn't an absolute necessity however you'll have the Snapdragon SoC which is a far better chipset with fewer bugs. For me it's the obvious choice if I were faced with your considerations.
You're most welcome

varcor said:
You're correct regarding Single SIM for the SM-G975F, the Dual SIM option is available in the SM-G975F/DS. I personally wouldn't consider obtaining a device in Israel if the majority of the time I'm the US. The major differences are SoC's, a minor difference in CPU Clock Speed and Cores. The SM-G975F has no FM Radio and offers fewer Primary Network capabilities. You can view a back-to-back comparison here.
https://www.phonemore.com/compare/p...gb-vs-galaxy-s10-plus-sm-g9750-128gb/10134260
This is quite different than your original question but with that being stated I would be confident enough in the SM-G9750's compatibility with the Israeli network for Wifi Calling. The worst case is not having Wifi Calling in Israel, which isn't an absolute necessity however you'll have the Snapdragon SoC which is a far better chipset with fewer bugs. For me it's the obvious choice if I were faced with your considerations.
You're most welcome
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SoC, meaning the chip?
You see, your definition of "worst case not having Wifi calling" is important to me , simply because where I usually stay in Israel there is almost no reception at all (inside the house I am staying in), that's the main reason I want a device that will be able to use their Wifi calling.
Also, I looked at the eBay seller that you mention and I don't even think he carries the O model any more, all I see is the F model, unless of course I am missing something.
Thanks.

sbi1 said:
SoC, meaning the chip?
You see, your definition of "worst case not having Wifi calling" is important to me , simply because where I usually stay in Israel there is almost no reception at all (inside the house I am staying in), that's the main reason I want a device that will be able to use their Wifi calling.
Also, I looked at the eBay seller that you mention and I don't even think he carries the O model any more, all I see is the F model, unless of course I am missing something.
Thanks.
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SoC is System on Chip, same as Chipset. If Wifi calling is a top priority buy the Exynos device to be certain but be advised there are numerous concerns over the chipset on XDA and other sites, plus Network Aggrigaton for Exynos in the US has issues with some T-Mobile clients. You may lose Wifi Calling or VoLTE in the US.
https://forum.xda-developers.com/s10-plus/help/exynos-att-t-mobile-t3920491
They still offer the SM-G9750, the link I shared is correct, not sure you missed something. The also sell the SM-G975F and SM-G975F/DS.