Calls always go to Voicemail

[NellG]

I have a Galaxy S8. When at home I have no signal so have set up Wi-Fi calling with preference set as Wi-Fi calls. Despite this incoming calls go to VM. Yesterday I reset Network and Settings and calls were OK but today they have reverted again to VM. 

[madasaf1sh]

@NellG

It sounds like your device is not respecting the defaults set.

Do you have the WiFi calling Icon on the screen when it goes direct to Voicemail?

[NellG]

No. in fact I cant see a phone icon at all

[NellG]

I just reset Network settings again and it accepts calls. Sounds if you are correct. How do I fix this?

[madasaf1sh]

@NellG

I would ensure you make sure all updates are done, other than that their isnt really a lot you can do, as the only other option which is a bit drastic is to factory reset the S8

[NellG]

So is it a phone hardware problem or a software issue? I have made sure all updates have been installed.