Why do calls go directly to voicemail after do not disturb is OFF

[TMW]

I'm on my second replacement samsung galaxy s6 (replaced do to bug in do not disturb) & if I use do not disturb feature, when it is OFF after being on, calls will still go directly to voicemail. I receive all other notifications. Verizon said it's a samsung issue, I went to samsung rep after receiving replacement phone & having same issue, & he said Verizon issue. I'm wondering if this is an Android issue. I cannot use the feature on both my original phone sent back & my replacement phone. Please advise.. Note a friend of mine has a T Mobile Samsung Galaxy S6, and when I turned her do not disturb on then off, she was still able to get calls.

 

[B. Diddy]

Welcome to Android Central! See what happens if you wipe the cache partition: https://support.t-mobile.com/docs/DOC-21095. You could also try booting into Safe Mode: https://support.t-mobile.com/docs/DOC-21007