iOS 12 comes with a weird bug which doesn't allow the iPhone to make calls. Some users of the iPhone pointed out a bug in the phone app which stops working or freezes unexpectedly. According to the reports, the issue is only found on iPhones and other Apple products running iOS 12. iOS 12 at first, seemed to be smoother and bug-free than iOS 11 but issues started popping out after months of release. The newly released 12.0.1 update didn't fix this bug. Users have reached to Apple for a fix, who suggested to perform a full reset of the affected device…. obviously this didn't work or was just a temporary fix. So all the affected users will have to seek Apple customer care for a fix or they'll will have to wait till Apple releases a Global fix.
Refurbished is not a used model rejected for many reasons but a brand new smartphone that is unused now, redesigned, remodeled, and still under manufacturers original warranty.