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Original topic:

Can't make or receive phone calls on an AT&T S20 Ultra

(Topic created: 04-30-2022 06:06 PM)
userRLofioEJFo
Cosmic Ray
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Galaxy S20

I have a two year old, AT&T cobranded Samsung Galaxy S20 Ultra, which as of today (4/30/22) can no longer make or receive phone calls:

  • When I try to dial out, the phone immediately goes to "call ended", as if I hung up
  • Incoming calls don't go through at all.  Moreover, the call hears that my mailbox isn't set up.  Normally, I used Google Voice for voicemail, and that had been working fine until today
  • All other features, including data over wireless and SMS, work perfectly fine.  That is, these work fine when WiFi and Bluetooth are disabled, so it's definitely connecting over the AT&T network


Troubleshooting thus far:

  • Tried rebooting the phone, going into safe mode, refreshing the connection from att.com/support
  • The phone and all apps are running the latest versions available - no updates pending
  • I removed the Google Voice app in case it was causing any issues
  • I tried using the MMI codes (e.g., ##61#) to disable forwarding to Google Voice, but get a connection error (801) when sending the code
  • Spoke with customer service on the phone and went through all their troubleshooting steps, including resetting network settings.  He eventually suggested I replace the SIM
  • Went to at AT&T store and bought a new SIM, which didn't help.  They did mention they have had other customers in this week with similar problems with other Samsung phones.  However, I can't seem to find anything by Googling around


Current status:

  • SMS and data work perfectly fine over the AT&T network (when disconnected from WiFi and Bluetooth) but still cannot make or receive calls
  • Tried everything I can think of short of a full factory reset
  • My wife's phone on the same AT&T account, and my work-provided AT&T phone, all work normally from this.  I've never had any connection issues in the past in this location
  • Phone shows 5 bars for signal strength, and connected to a 5Ge network
  • From the SIM card status menu, Mobile Network State = Connected, Service State = In Service, Mobile voice network type = LTE
  • Phone = AT&T co-branded, network locked, SM-G988U

The guys at the AT&T store suggested waiting for AT&T or Samsung to push out a fix for the issue, since other people have had the same problem.  They said when they contacted the AT&T home office, the person they spoke with said they were aware of the issue.  However, I haven't been able to find anything online about it - you'd figure if it was a fairly widespread issue, there'd be forum posts or news about it somewhere.

Any suggestions on next steps?  Full factory reset isn't really an option - I'd sooner buy a new phone and make sure I've transferred everything successfully before wiping my current one.

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userRLofioEJFo
Cosmic Ray
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Galaxy S20

Familiar enough, I guess.  I can poke around in settings and MMI codes, generally, but don't always know what those options are 😛

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userRLofioEJFo
Cosmic Ray
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Galaxy S20

Worth mentioning: one other issue I've identified since the original post is that my IMS registration status is "not registered".  Some sites I've seen say that may be relevant to voice over LTE not working.  I did call AT&T about that and they had no idea - they had to submit a ticket to their support team.

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Cass94
Nebula
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Galaxy S20
Yeah I mean something should be showing not connected or registered again my theory is you have corrupt files that keep getting reloaded that are causing the incompatibility
Cass94
Nebula
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Galaxy S20
Sounds good first off your using another phone to message on here right? Because we'll be rebooting a couple times at least
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userRLofioEJFo
Cosmic Ray
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Galaxy S20

On a PC for the msg boards, yes.

Cass94
Nebula
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Galaxy S20
Okay lord this would be so much easier if we were on a messenger I'm gonna be throwing a lot of instructs your way lol
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Cass94
Nebula
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Galaxy S20
I only ask so I don't overexplain things you know
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Cass94
Nebula
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Galaxy S20
Couple quick questions... do you use wifi calling? And are there any settings that you know you changed that would have anything to do with phone calls or any apps you use for calling that aren't stock
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userRLofioEJFo
Cosmic Ray
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Galaxy S20

I don't normally use WiFi calling.  I did try to enable it today as a workaround for the lack of phone calls issue, but it didn't work.  The error I got when trying to activate it led me to the IMS not registered issue.  I called tech support and they had to escalate a ticket around it - said it'll be 24-48 hours to resolve it.

That's after getting a new SIM, and I had thrown the old one out.  I don't think I ever used WiFi calling with the old SIM, and I don't know if IMS registration was an issue with that one.  I'll probably head back to the AT&T store tomorrow to see if they know, or maybe tried a third SIM.

I use Google Voice for voicemail, and have call forwarding to send unanswered calls there.  I tried to disable the call forwarding, etc., when this all started, but the MMI codes (e.g., ##67#) aren't working - network error.  I did try deleting the Voice app and restarting.

I also use Hiya for caller ID and blocking.  I also deleted that app when this started - no luck.

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userRLofioEJFo
Cosmic Ray
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Galaxy S20

Beyond that, no weird settings.  Random blocked numbers, and I block unknown/private numbers.  Removed those settings already, which didn't help.  I use the stock Samsung dialer/phone app, otherwise.

Booting into safe mode seems to have deactivated anything that wasn't stock, but that didn't help.

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