About 2 1/2 weeks ago, I started missing calls because my phone wasn't ringing and calls went straight to voicemail.
For some of the calls that come in (including Telemarketers unfortunately), I hear the ringtone while others go straight to voicemail. A work colleague has called me and a few times the phone rang and the rest of the time his calls went to voicemail. It appears to be completely random and not associated with certain numbers, people in my contact list or calls during certain times of the day.
I've had my phone for about 9-10 months and although I had other notification issues with it (which I eventually solved), I always heard a ring tone when a call was coming in up until about 2-3 weeks ago.
I've checked all my settings and did some troubleshooting of my own
1. Volume for all notifications is turned up (Do not disturb is OFF)
2. I don't have any calls blocked
3. I don't have call forwarding (in fact, that option doesn't even appear on my phone in the settings menu! What's up with that?)
4. I don't have any apps blocking or monitoring incoming phone calls
5. I can make outgoing calls
6. I've turned the phone off and rebooted it (no change)
7. I've removed the SIM card and put it back in followed by a reboot (no change)
Furthermore, some of the calls that come in (when the phone doesn't ring) don't show up in my call log so I have no idea who called or when. If they leave a voicemail, then the voicemail eventually shows up in the call log but not all calls show up in the call log! That too appears to be random.
I called T-Mobile Customer Service and got someone off-shore who was clueless and told me to reset my phone to factory settings and sent me instructions for a Galaxy S3 (I have an S6).
I use my phone for business and I can't afford to miss important calls! Any help is greatly welcome and appreciated.