I'm not receiving visual voicemail messages reliably on my iPhone 6S under iOS 10.0.1. Sometimes I don't receive a notification, but the message is in my inbox and there's a badge on the Phone app icon. But sometimes I don't receive a notification because there's no message -- and the message might arrive after a restart.
Is this a problem with T-Mobile or with Apple? I have tried troubleshooting with T-Mobile tech support, to no avail (they say that my accoutn is correctly configured). I do have version 25.1 of the carrier settings file.