Phone won't make or receive calls

My samsung s8 is also having the same issues, not able to make or receive calls. All else works. Got new sim card and headphone reset. Still not working. Very frustrating. Not happy with ATT.

@Itsgwerner

Is it originally an AT&T phone?

If the model number is not exactly Galaxy S8* (G950U), updated running correct software, it can't work

After an hour on the phone with ATT advanced support, the representative finally let me know that 100% of BYOD (Bring Your Own Device) are not working / or will not work on their LTE network, regardless of 5G, 4G LTE or not.  He said he has a message from his internal team that going forward no BYOD devices will work or be supported for LTE voice calling.  That's pathetic.

I can get the system to work (make calls) per Woodb01's comment above -  Moving the network preference off of LTE to TDSCDMA/WCDMA, but that is not what I am paying ATT for.  Is this really the go forward policy for ATT?  I just spent $1,500 on a new MSFT Surface Duo 2 directly from MSFT.  ATT shows the phone as a supported phone, and MSFT claims it fully works on ATT, but evidently ATT isn't telling people the truth about what is supported and what is not?

@aphelion

After an hour on the phone with ATT advanced support, the representative finally let me know that 100% of BYOD (Bring Your Own Device) are not working / or will not work on their LTE network, regardless of 5G, 4G LTE or not.

🤣.  

False.

There are tons of BYOD that are working just fine, with full services.

What may be true, is that 100% of the phone calls that particular representative is receiving are from people with non AT&T phones. Which is only based on his narrow perspective, but it is not true.

@GLIMMERMAN76  has a dozen non carrier phones which work perfectly on at&t

How old is your sim card? 

I am just stating what the AT&T technician told me. To your point, my voice calling did work for a few weeks post the 3G roll back, then stopped working after returning from international travel, or from doing a watch phone number sync (not sure which caused the issue as both happened simultaneously.) I will go get a new SIM card today, but from what I am seeing online, and what the technician told me, that will not solve the issue with BYOD phones.  Since voice calling does work on the TDSCDMA network, the issue likely has to do with ATT's LTE network.  Why it stopped working is beyond my understanding, but I tend to agree with Woodb1 above that there is an underlying issue with ATT LTE that they need to fix.  I'll let you know if a new SIM card solves it, but again, hasn't helped most of the similar posts I've seen.  

OK - so I was wrong.  The new SIM card solved the issue and phone calls are working again on LTE.  Oddly though, there were two other people in the store having similar issues, one an ATT employee.  All had BYOD phones. Unfortunately for one of them a new SIM card didn't work.  Not sure what's going on but appreciate the heads up and solution, at least for some of us.   Thanks!

Not all phones are on the usable list yours is so I can see a new sim clearing it up.

Just updated my SM-G973U1 to Android 12 and lost ability to call/receive calls. VoLTE is provisioned. Had to resorted TDSCDMA/WCDMA for the sake of at least having 3G and resuming the ability to make calls.

Still waiting to hear back from AT&T directly which seems like it's to no avail from the sentiment of this thread. Before I waste any more time, you guys are saying my first step is to go try a new SIM card? Just trying to get the speeds I pay for back... is that not possible without reflashing with an AT&T image?

I just came back from the ATT store, it took 5 min to replace the sim card for my phone. Unfortunately that didn't fix anything for me.

At this point it either use 3g while it works or buy a new phone from them. The supported list that the company put out is useless. On the ground reps say that they can do nothing about this issue.

Sad.

@boggle you have a G973U1 and you CAN NOT make calls after upgrading to android 12? weird, updating to android 12 was what FIXED my VOLTE.

make sure your preferred network type looks exactly like mine. another member checked her settings and matched mine and she was able to call again.

and yeah, make sure you have one of those newer "blue and white 5G SIM cards". not the old orange and blue ones... even though those would technically work as well.