WIFI Calling Preferences Being Forced to Cellular Preferred

Solved! ! ! Not certain how may people are still having this issue since Android Pie update but I think I have found my solid working fix for WiFi calling continually flipping to cellular preferred, I am on TMO Samsung S8 Active but from the sounds of things this should do the trick for many other carriers or devices if any others could please followup with further testing. After trying numerous other discussed attempts and further digging I found out all I needed was a simple tool I already had from battery saving mods, no ROOT is needed at all but can be accomplished just the same if you are. First step coming closer to making this work, I turned off WiFi scanning by searching for it in the general settings menu of android, this is to help avoid any extra unneeded wifi signal interuptions, not certain how well thia plays with any "companion device" users but may, I have no purpose for these. I use Greenify and Island to debloat/disable unneeded apps from my user interface that application manager fails in ability to do, a computer with ADB installed and options enabled for such in Developer Options, search XDA for setting these up, most of this was just for battery savings essentially and is unneeded but good help. The app I installed which I found fixes our issue is App Ops - Permission Manager from play store, using a computer loaded with ADB and dos/command prompt terminal to send commands to grant needed permisions. Once in App Ops, make sure system app options are checked and scroll down almost all the way to the bottom to find your systems WiFi calling app and set "coarse location" option to "ignore" to prevent network scans from triggering this hated event and then also set the "modify system settings" option also to ignore blocking changes from occurring. I also have coarse location on my Phone app set the same too but I don't think it matters on that app, I had set the phone app previously as such with no effect until tweaking the permissions on the WiFi Calling app itself. Using App Ops I find you must reboot also for permissions to take effect. I have multiple wifi routers setup and hotspots from work I used to try to force a change-over to happen as WIFIs change or diminish out of range(as this function is implied with its label), my WiFi Preferred calling method is now finally under control. If you choose to use App Ops to resolve this issue or expirement with the others, only use the suggested options for the WiFi Calling app, all other options I tried on it either crashed the app or breaks IMS Registration otherwise which is needed for Video/VoLTE/WIFI Calling features. Tweak/debloat any other apps you wish to save battery/data at your own risk one by one, especially any other features in App Ops, very easy to break functionality of any of these or other functions if you tweak too much all at once like I did to try to fish through what messed up something else(good thing theres a select all/restore to defaults option) tweak little by little if you do, I was one of those standing at the store and on tech support for endless hours set on it being my out dated sim card then 2 new sim cards doing the same before finding out I tweaked to many settings same day I had got my new sim card

EDIT: Noticed it still flipped once in the middle of a meeting. I now made one last adjustment in App Ops for Wi-Fi Calling app setting the "Change Wi-Fi state" option to ignore, and another reboot. Will see what happens but I have verified while connected to an active wifi router, I unplugged the modem, Android status bar showed internet connection not available, bounced between this and my hotspot a few times back and forth, "Wi-Fi Preferred" selection is holding through all without any other intervention or pesky notifications, also while connected to dead wi-fi calls went through no issue from cell data while my meeting disconnected looking for wifi, also stretched out my hotspot to minimal signal detecting 2Mbps wifi speed with my meeting lagging out and full cell tower bars, now this actually fits the definition of WiFi Preferred, status in call settings now only changes to "Currently unavailable" occasionally if when travelling to outskirts of actual wifi signal and re-connects persistently as Wi-Fi Preferred once in adequate wifi range, partnered with a proper mesh wifi setup seems to be working properly smoothly for once

As others have said elsewhere, this is kinda almost a global developing thing between "consolidation" of networks between massive amounts of cell service carriers further developing as they merge, anything running Android 9 or newer unless its a custom firmware/rom or maybe some early Android 9 rollouts. Been happening for years depending what you're running. Check out Verizon's status here:

https://community.verizon.com/t5/Google-Pixel/How-do-I-force-wifi-preferred-for-wifi-calling/td-p/1086338/page/5

If you have an old phone and sim thats active prior to these issues you may be in luck foe the time being but just as I find with tmo you have to start with a new sim card or when you "upgrade" with a replacement, newest are 5g compatible but features get locked out in phases in this process of which a carrier determines is no longer supported as with whats happening to 2g/3g type devices currently. People been battling it for years between em all. You can fix it yourself with the help of a pc with less a tenth of the characters in the command prompt that it took you to respond or continue to wait with the others as they have for years. Only part i get on the Verizon thing is overall coverage area, each has their dead spots so i roll with a Verizon Jetpack from work for that matter. Everything I did a factory reset clears all, my point I never reset my phone once since the day I bought it. In the long run i have a fully functioning phone with everything working, multiple work accounts syncing smoothly with all nonsense silenced, the apps I use are thouroulghly developer tested, widely used, and google play store certified. Do you really think its usefull like Microsoft and Google both branched together to do and upload every sigle device's user data to "their" cloud"? Using my phone as a PC as an IT tech pretty constantly all day, I'm satisfied with less than 25% total battery use for a usual day, probably will be a bit better than that now that I won't be redialing calls constantly and fighting between menus or missing important calls from my hospitals or schools while working at them. Yes there are bad apps out there, do your research for what you choose, Im a tech who doesn't take care in time to wait on industry and gave up on any companies status on customer support decades ago, i fix what i need to fix with proper research where needed. 

I just got off of chat with support and have a solution that works so far. I had to have an e911 address set to keep it in WiFi preferred mode. If I had to guess, I'd say it's a safety precaution so that in the event you call an emergency number when not connected to a tower, they know where to send responders. The agent set the address for me, but I also see the option to set it yourself in the wifi calling options.

Having an E911 address set in the first place is the first essential part for Voice over LTE, video calling, and WiFi calling features to become active and usable at all in the first place, otherwise yours was functionally disabled without it, even though the toggle is there, with no E911 it causes IMS registration to fail, dis-allowing these functions entirely from the cell tower on device bootup. Testing with Airplane mode on then wifi, calls will drop regardless if E911 address is not in place, IMS Registration status is verified in SIM card status will tell you if Voice over LTE, video calling, and WiFi calling features are active and functioning Now that you have it, it WILL be a matter of time until you find this setting changing to cellular preferred constantly occurring throughout use as most ALL other carriers included Android 9+ Google software bundled phones go. Tracing through logs in App Ops I have identified this change over issue down to a combination of all softwares, implemented first by Google through most any Play Store apps eventually brought into standard Android OS development and also infused into vendor/carrier installed apps just the same is the ongoingly largest battery draining issue - randomly occurring wifi scanning also mixed in with Geo Location/NFC triggers which are all binded directly with GPS Location Services function. Bottom line primary trigger causing "Cellular Preferred" changes is limited consistent Wi-Fi internet data throughput or bandwidth, this by absolutely no means is wifi signal strength at the router but combination of all specifically between the modem itself and the wifi calling app itself on your device, home modem internet signals are rarely consistent although your wifi might be bad ass at hiding it for other types of devices; this can all drastically be affected also by excessive Google/games/apps limiting bandwidth to wifi calling app also multiplying the issue also having wifi scanning built into everything.  Wifi scanning basically momentarily pauses or severely limits your current wifi connection while the radio adjusts between wifi channels trying to locate other networks to meter yours against, causing the wifi calling app to disconnect unexpectedly and flip to cellular. This in turn blows for us all because it is implemented into almost all newly developed/updated apps to be allowed in the Google Play Store, even the built in Android app that senses input from a simple touch of your touch screen and keyboard apps cause wifi scanning to momentarily take place, had mine changing it seemed 50% of the time swiping my screen to unlock. The standard Android settings menu allows you turn off wifi scanning so they make it seem but this toggle only disables wifi scanning features at user level installed apps, not wifi and GPS scanning for system based ones provided by Android/vendor/Google. Only time when wifi scanning ideally should be occuring is when you are in your list of connections making a choice to connect to. Appops is implemented into all versions of Android already at the command line level as DOS is to windows so it works as a one-time direct command adjusting permissions/settings directly and instantly, not like other apps which run receivers to trigger scripts continually draining battery/hindering function. Play Store App Ops gives you the graphical interface to utilize it easily(internally utilizing ADB at boot sequence to apply changes all at once or all can be disabled just the same if issue were to arise tweaking without research), allowing you to directly set system app and user app permissions to ignore these requests with blank data(rather than blocking and crashing app). The only select few apps I set to allow location access to is Google Maps cloned along with google play services, isolated in my cloned Island work profile for when needed , then two I set to "allow only while using the app which are both needed for IMS registration to successfully complete at boot: DiagMonAgent and IMS Service. Since IMS registration takes place only once on devices at bootup, if I have wifi left on before rebooting it may trip to Cellular Preferred only once just at this moment depending how fast wifi connects vs completion of IMS registation. So as long as I don't restart with wifi on my issue is now 100% resolved and now completely entirely non-existent, "WiFi Preferred" calling mode is now holding persistently, only now accurately displaying unavailable currently when wifi diminishes before dropping or as changing WiFi to another connection, IMS re-establishes and maintains "WiFi Preferred" option through every transition. The other guy can above can run back to Verizon if so he chooses but either way we ALL live in this Google/Microsoft driven world whom both want to know every last detail of none other than you, good luck getting them to change their ways or to get your new carrier to sell you a device that has neither but works on their network, otherwise mod your own device you personally own how you like the way, we in the free/open-source Linux community, always have. Windows 95 does still function also if you so choose to use it for something or like demonstrating how things USED to work in days of ol, but if you want to use it with today's world of software and hardware both, you won't have much luck.  If you merely buy a device from any standard Cell Phone Carrier you are in fact buying into their whole entire knowledgeably ignorant scheme to hand them hundreds of dollars only because their service is somehow unexplainably "better" than their identical competition with identical devices and consolidated shared Cell towers, sales are not developers are not technicians, continue the endless loop. Open source already fixed the problem, Google and Microsoft never will because it is 100% strictly marketing based and profiting them, if a product doesn't work well or no longer does after being updated to "latest improved software" you'll come shovel out hundreds for another new one to replace a 6 month old new one….right??? There are other forums for those carriers too once you find yourself in the exact same current situation once your new device updates itself. Also good preventative to avoid vendor forced OS updates that some have found their devices booting up to regardless of disabling automatic system updates (vendor/carriers do have the ability to and do force system updates occasionally in waves to all devices reporting not being updated after a set time duration expires pushed through SMS/GMS code in the System Update app) if using Island then freeze (disabled until YOU open it)the update app and only update once you know updates are stable, most vendors wait months after security updates are released before they push them to available for your device to see in the first place so a little extra time on your end to actually verify stability between other actual users will keep this and any other unexpected downgraded updates from disrupting life

IT looks like this has been fixed.  The latest update for My S21 leaves WiFi preferred, locked in. 

The issue appears to be: how can you advertise a feature that clearly does not work? The old "truth in advertising" problem. I think that correcting this issue should be a technical priority for T-Mobile.

I'm having the same issue, and I never get more than one or two bars at my house. The only thing that works is Airplane mode and turning the WiFI and WiFI calling back on. This is a terrible solution, but the only one that works.

I agree that it is likely some TMo bloat/firmware that is doing this since the VZW phone I was using didn’t have the problem.

Yes, I knew that they were likely just trying to get rid of me.  Since I'm retired I can take the time to go to Level 2/Manager support.  That is a task for this week now that I've done my research.

In the mean time I'm trying the Tasker hack that is supposed to automatically turn wi-fi preferred on if anything turns it off.  I don't know yet if that is going to help, but it is worth a try. 

Samsung support said that this isn't their problem since all wi-fi calling features are carrier specific.  I had to try.

I don't know if there is a root for the S22 yet.  Even if there is I probably won't do it yet since with a new model there is often a flurry of stock firmware updates for the first few months.  I've read that there is one coming.

WiFi calling and HD calling rolled out on Sprint before my GS8 replaced my GS3, and it worked flawlessly. Handoff from my killer WiFi to cellular & back no problem, ever. Even in my expanded-wire plaster, wire & lathe walls (1940's) WiFi calling gave me HD calls all over the house …

… now disabled, a phone means life even more than the 'maybe I need 911' of years past. The merge got me my first T-Mobile SIM -- and bad WiFi calling, so I went back to the Sprint network, until I had to go to a new T-Mobile SIM -- WiFi calling was improved … but I'm now in 'preferences' v. 'settings' land like most every post here. Been to tech support -- forced to the Sprint side. Pushed to buy a phone at every turn, go to iOS, completely migrate to a T-Mobile account … get a Cell Spot.

No reason to expand TMo's 4G-LTE by giving them free data, free run of my LAN, and free power, for an unregulated, unlicensed, cell tower, which will shut down as soon as power fails. I currently do better with my Ooma VoIP setup.

In my case, TMo 4G LTE is usable 1 meter inside the house, entering from the east (front). The middle is a 4G dead zone. The north window in my office can see 5 bars of ATT 4G LTE and tries to use it - but the power drops to minimum necessary, saving bandwidth, triggering a switch back to WiFi -- after a few rounds of WiFi/AT&T ping-pong -- all cell connectivity is broken, and my number is "unknown" to all callers -- no texts, no voice mail , no calls, in or out -- but I can still browse the web just fine -- I must restart my phone to restore service.

Done the support orbit for two weeks -- same exact story as everyone else.

I suspect that Samsung struck a data deal with TMo, that must use cellular data to satisfy, because if it used WiFi, it would be trivial to snoop and see what’s being forwarded … if this hypothetical is in any way correct, we’ll be very unhappy with such a dark alliance.

So, TMo and AT&T are not playing well together --- but what can you do?

This is a patch - it's ugly - but it will keep you online and able to use 911 in an emergency, without a restart and a password. Three steps:

1. settings→connections→WiFi→[three-vertical-dots, upper right]→advanced→switch to cellular→off

Now, go someplace where you do have TMo coverage, or this will glitch.

2. settings→connections→mobile networks
   1. verify that T-Mobile is the Network Operator
   2. set it manually if you must
   3. Data roaming→off

Último paso

3. settings→connections→data usage→mobile data→ off

With those 3 settings in place, my GS8 now pesters me relentlessly with a system dialog asking for permission to search for a better data connection -- why my WiFi isn’t ‘supremely endowed enough’ for their liking is impossible to fathom without considering hypothetical situations such as those expressed as my personal opinion above.

I'll happily ignore and cancel a fast system dialog that self cancels as you type a text or e-mail. Far less painful than 6 reboots on a Sunday afternoon. It keeps me from getting kicked to the curb by AT&T, which clearly does not approve of playing ping-pong - it's a waste of cellular setup resources - the most expensive connection in the game - no wonder they kicked my T-Mobile data-roaming to the curb.

Side note, the phone won’t scan for other Cellular Data networks if it’s connected to one, so this happens only in fringe cases and ‘sturdy’ construction -- and no, 28GHz and 39GHz 5G won’t do any better - it will do far worse - you’d need 100GHz to walk through the mesh in my walls, unscathed.

I’m unhappy, have been disrespected, and unacknowledged.

I'm patched well enough for now -- but it's not a solution. As far as I'm concerned, I'll let the US DOJ have an image of my phone's firmware …