Calls not possible with Galaxy S8 on one network

[Android Central Question]

I've got a sudden issue with calls not working anymore with my Galaxy S8. Strangely enought Text and Internet Data are fine.

I've tried switching Sim Cards and the phone itself is fine as the sim from another provider is working fine in the S8. The sim from Lebara/Vodaphone which is causing problems with the S8 is working fine in a Galaxy S7.

I've been in contact with support from Lebara and they've asked me to get another sim for them to port my number to.

This didn't solve the problem. I've also done a factory reset on the S8 to no avail.

Any ideas what might be causing this?

 

[methodman89]

Can you make calls? Is your call forwarding switched to 'always'?

 

[Mautje_oz]

Thanks for answering,

No making calls is not possible either. It's really all voice that is not working anymore. I've disabled Wifi calling in the mean time also disabled Advanced LTE but that didn't help either.

I've been searching the net and I've seen more complaints about Android Oreo acting up but have not been able to find a working solution yet.