Yesterday I updated my iPhone to iOS 10 and now I am unable to make calls over my carrier (T-Mobile's) network. The error that shows on my ring central app states that VoIP calling is unavailable. This feature worked fine before the update to iOS 10. I am not interested in using my Wifi network as the call quality degrades significantly. At this point, it seems the only option is to use the ring out feature which is very buggy at best. Is anyone having this issue? Any advice to help sort this out would be greatly appreciated. My gut tells me this is an iOS issue that will need to be resolved with a ring central app update.