I'm having the same problem, only it's happening upon first startup. I can't even create an account when trying to log in for the first time with a new number.
I know this issue has been addressed numerous times on many forums. Often whatever solution is provided works for some but others say it did not work for them. I've done my due diligence and there must be something particular to my situation. So here are as many of those particulars as I can...