Help Flashing ATT U Firmware on T-mobile S20+ SM-G986U - Samsung Galaxy S20 / S20+ / S20 Ultra Questions &

It has been a while since I've spent time on XDA. I haven't flashed a phone since the HTC One M7. I had to switch carriers from T-mobile to AT&T not long after I had purchased the S20+ for T-mobile. Most of the features work on AT&T, but I'm lacking the VoLTE, Wifi Calling, and Visual Voicemail that I would really like to get working. Can someone recommend an up to date guide that can safely guide me through the process, I'm sure its not that complicated, but I have been away from the scene for a while and I really don't want to end up with a bricked device or accidentally pop an e-fuse (if thats still a thing).
I appreciate any help, advice, or direction that anyone can provide.

Related

[Q] PLEASE Any way to flash to Cricket?

I have been searching for months and I see a TON of posts where people say they HAVE flashed to Cricket (and discuss their various problems), but I am unable to find ANYTHING about how to flash to Cricket. Every lead is a dead-end. They either bring me to pages that do not work, or people who want me to send them my phone. I get that this phone is old and maybe that is why all the links are dead? But any help would be much appreciated.
As far as concerned currently you can't. Ever since AT&T bought it they've allowed certain use of cdma. But as time passed on they were mostly focused on gsm over cdma. Therefore currently only the people with grandfathered plans may use cdma. If not then they have to have a AT&T phone or an unlocked gsm phone to use their services. Long story short yes there was a way to flash to cricket. But not anymore :/ sorry about that bud. But small heads up! If you find the AT&T version of the phone you dont even have to unlock it!

Rooting and custom ROMing a unlocked phone on different carrier.

I finally upgraded my phone after 4 years with the old htc one s.
So I am very used to flashing that phone and ones similar.
I got this at&t version of the LG G4 for use with T-Mobile (US).
It came unlocked and all I had to do was put my sim card in and talk and text worked. Then set up a new apn profile for T-Mobile and everything else seems to be working fine.
I am about to embark on the whole rooting and flashing a new rom on it.
Was just wondering if there was any advice to consider before diving in.
I have done a decent amount of rooting and from what I can see, this phone doesn't really look to hard for the most part.
I noticed that there are different sections on he development forum for the different carriers.
But I am going from one carrier to another and would rather have a T-Mobile rom as a base. ( it think I am going to use a mostly stock rom. Just to see what LG has to offer.)
Is there any problem with flashing a T-Mobile rom on the att phone? also a T-Mobile radio?
Forgive my noobness, its been a while. "This almost never happens"
Also any advice for the easiest rooting technique. maybe a good video to watch.
I will do the research. But a nudge in the right direction could save a lot of time.
Thanks.

[Q] What's the cutoff point for ROMs to unlock the SIM?

OK, so I have an opportunity to get an LG G5 LS992 Sprint model today for a decent price (under $60), with box, original cable, charger, accessories, 2 or 3 cases, looks to be in fairly good condition from the pictures. The girl selling it doesn't know how to answer most of the questions I have so certainly I can't get her to tell me what the ROM installed is by looking at the Settings - About phone info.
So here's my question: been doing some research today into the current situation and from what I gather, Sprint, in their infinite greedy and stupidity as usual, has found a way to block the ability to unlock the SIM for use with other carriers like T-Mobile (my carrier of choice). Apparently this started with ZVC and I have no idea which specific version of Android that is since there's a bunch of them around but I'm going to presume it's at least Android 7.0 Nougat.
I'm going to presume that if this phone does not have ZVC on it then it's safe to also presume that I would be able to do the SIM unlock and make use of it with T-Mobile so if anyone out there might be able to answer that I'd be eternally grateful.
As stated, I have no idea what firmware is currently on the device, unfortunately, I sure hope it's not ZVC or anything later, guess I'll find out later today when I meet up with this person.
Dammit, Sprint, what the hell are you people doing?

H8314 on Verizon: what to do with a Global version

Hi all,
I'm brand new to the forum so forgive me if this has been already been hashed. I generally try to do fairly comprehensive due diligence when buying phones but this has left me completely exasperated.
I found out, the hard way, that the H8314 comes in two versions - US and Global; I suspect I ended up with the Global. The hard way was bringing my device to Verizon and after over 2 hours of toil being told the device was "locked". I'm therefore stuck with a useless phone as the global version will not register on Verizon. It does activate on AT&T but because VoLTE is not supported it will downgrade to G3 for voice and calls on those bands are highly unreliable. Anyway, GSM and CDMA will soon be gone so there is really no viable and durable option in the US for this device.
My question is there anything I can try to salvage this phone Is it possible to flash a Verizon compatible kernel that might rescue it? Any other ideas?
Thanks in advance!

I have been out of the game for a while but I was hoping one of y'all could help

My son had a T-Mobile branded S20 5G and I moved our service to Verizon. I paid his phone off and got it unlocked. Everything was working fine up until a couple of weeks ago. He did an update (didnt pay attention to what kind of update) and now he cant make or recieved calls or text (keepin mind the phone was working fine before this update). Attempts to call result in a message from Verizon saying that they cant authenticate his phone.
I *****ed at Samsung for a bit since his phone isnt rooted and even though its over a year old if a software update bricked it, I felt like they should have some ownership of the issue. It was a waste of time so now I'm back on the phone waiting for VZW tech support.
I think the issue is that its a TMO branded phone on VZW's network and everyone is pointing the finger at everyone else. My question is 2 fold.
1) has anyone ever experienced this before, and if so what did you do to resolve it and
2) I will attempt to root it and flash a ROm on it before I entertain buuying another phone.....hes got enough other **** hes dealign with financially he doesnt need to add a new phone purchase to his plate.
Any help would be much appreciated because I'm pissed the eff off at this point.
Yes we tried different APN settings...he walked into a VWZ store and they were able to get his data working but not voice or text....seems like something is out of whack with his radios). We also did a full factory reset.....same issue persists
I am not an expert on ROMs but I will give you my two cents. When I was playing with my unlocked phone, I realized that mine updated some CSC binaries as soon as I inserted the SIM. I saw some message for it updating the CSC code from XAA to TMB when I inserted TMO SIM on stock firmware. So my suggestion would be to try downloading VZW stock firmware from samfw.com and installing that.

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