Calls disconnect, phone doesn't ring and texts delayed.

[MrAt]

Since "upgrading" to the S20 Ultra from an S9 Plus, I am finding the following issues:

People calling me cannot connect and get my voicemail as soon as they dial, even though the phone is always on. 

When I am on calls to people, they will go quiet, then the call will end after about 15 seconds. 

I am getting around 2 to 4 bars of signal (meaningless I know) whereas I was always a steady 4 or 5 on my old phone.

My partner called me ten minutes ago and could not connect, sent me a text which I did not get for ten minutes. I called her back, 7 minutes and 47 seconds in, the call drops. I have to call her back again. 

I am currently working from home and have missed a few important calls from my work due to this phone. 

I have contacted Three who suggested I reset the networking settings which I have done and this has not helped. 

I am on the latest firmware 

I do not expect this kind of behaviour from a £1400 phone. 

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****NOT SOLVED****

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[ChrisM]

That's not what we like to hear, @MrAt. Is the software on your phone up to date? Go to Settings > Software update > Download and install. Also, let's try a soft reset on the phone. This will end all processes and give the phone a fresh start. Press and hold the Volume Down and Power keys at the same time until the phone switches off and back on again.

Let us know if this helps!

[MrAt]

The software is version G988BXXS2ATD5 which is the latest version.

I have just tried the soft reset and will monitor. 

Thanks for the help so far. 

[MrAt]

That made no difference. When I called my number, I got silence for about 10-20 seconds. Nothing rang my end, then I got my voicemail.

[TessM]

Are you able to place the SIM back on your previous phone and let me know if this is still happening @MrAt?

If the SIM is operating correctly on your previous phone, can you try your phone in Safe Mode and monitor it for at least 2 hours to see if a third-party app is causing this to happen? To do this press and hold the Power button until you see Power Off, Restart, and Emergency. Press and hold the Power Off icon until it shows a Shield, tap the Shield and the device will restart in Safe Mode. 

[Patrick]

Put your Simcard in slot 2 and let me know if it works

[MrAt · Accepted solution]

The sim works fine in my old phone. Also in a nasty cheap LG I have as a backup. I have tried safe mode and it was in this mode, set to air plane mode to try wireless calling. My partner called me, the call lasted 3 mins before I lost the call and wireless calling stopped working. I was unable to call her back until I disabled safe mode and took it out of air plane mode and was able to call her back and hold a conversation. This is not the first time this has happed too. I have a fast and non contended internet connection at home.

The problem is intermittent. It seems to happen when I have not used my phone for while.

I have both soft and hard reset the phone.
Tried the SIM in another phone.
The phone is in an official Samsung case bought directly from Samsung.
Tried Safe mode
Updated to latest firmware
Also tried several incantations over the phone, trying to summon the phone spirits with incense and cheap candles from the pound shop, to fix the issue but this was as useless as everything else.

I think I might try what this guy suggested:

https://eu.community.samsung.com/t5/Galaxy-S20-S20-S20-Ultra/S20-ultra-signal-keeps-dropping/m-p/167...

[MrAt]

So far so good. I had a call from my partner and it connected without issue and I was able to hold a conversation without the call dropping. 

Seems it is the wireless causing the issue. I do hope Samsung will release a fix soon, while I have a lot of data, it's not unlimited. 

[cgavrielides]

I had the same issue. I struggled for a month and a half with Samsung Support and tried everything, even changing the SIM.

On the second time the phone was with them, they put it through more testing, and they managed to replicate the problem. They eventually agreed and changed my Samsung S20 Ultra for a new one. The new one has been fine so far, but this was a dissappointing experience, to say the least.  

[Avgoustinos]

I found a possible fix. My ultra was not receiving calls when left in idle for 20 mins. Also noticed that when activated from idle state and turning off wifi, then it received calls.

So i went on and investigated whats going on when idle. I placed the phone in optimised mode and stopped the adaptive power saving feature. Left it on idle and notticed that ONE UI app is always running in the background...went to apps》ONE UI HOME》Permissions. Mine had everything in Denied. Moved everything in allowed and now i am receiving all calls. 

Hope it helps, let me know on your results