I am having this same problem with a Galaxy S7 Edge. I've searched these forums, and tried everything. Sim card remove and re-add... I called support, they got the notification to go away for 15 minutes (by resetting my voicemail - and I had to go back in and set everything up), then it came back, so I never called back. Let me follow this up by saying this has been plaguing me for YEARS, and has followed me across multiple phones. The notifications started getting worse (more frequent), and I can't trust my phone anymore. I'm being pushed to the limit of my patience. If this doesn't get figured out, my next step is to take my numbers to a new service.