I researched this problem on a number of forums and did not see a definitive FIX. I also called both Verizon Wireless Support and Samsung Technical Support. After following there useless suggestions for almost two hours, I finally decided that clearing the Cache might fix the problem. Please understand that I must use Wi-Fi calling at my home to make voice calls that do not drop.
Unable to connect to wireless carrier and make outgoing calls or receive incoming calls using WIFI calling option after upgrade to Oreo version 8.0
I live in an area with very poor celullar voice coverage. By using the WIFI calling option I get great call quality and no dropped calls.
When some-one tries to call, their call goes straight to voice-mail. You Cell phone will ring and there is complete silence when you answer.
TO ACCESS WIFi Calling FEATURE:
Settings: Connections: Advanced Calling: WIFI Calling.
CAUSE OF PROBLEM: Some caches may have been corrupted and one of them may have been the cache for Wi-Fi. The thing with caches is that you can delete them and still expect nothing will happen with your device, however, when they get corrupted and the new system uses those corrupt files, issues like this may occur. So, we need to delete them so the system will replace them with new ones and this is how you do it:
1-Turn off the phone.
2-Press and then hold the Home and Volume UP keys, then press and hold the Power key.
3-When the Samsung Galaxy S7 shows on the screen, release the Power key but continue holding the Home and Volume Up keys.
4-When the Android logo shows, you may release both keys and leave the phone alone for about 30 to 60 seconds. Sometimes another odd message will appear. Just wait longer until the list of options appear.
5-Using the Volume Down key, navigate through the options and highlight ‘wipe cache partition.’
6-Once highlighted, you may press the Power key to select it.
Now highlight the option ‘Yes’ using the Volume Down key and press the Power button to select it.
7-Wait until your phone is finished wiping the cache partition. Once completed, highlight ‘Reboot system now’ and press the Power key.
8-The phone will now reboot longer than usual.
After this, try to check the Wi-Fi calling option works by turning on the feature and see if you can make an outgoing call. If this works have some-one call your phone and see if the call goes through.
When I finished clearing the cache, my phone connected to my home network but showed no Internet connection. I had to re-start the phone to get the Wi-Fi connection to access the Internet.