phone won't ring calls go straight to voice mail

Same problem for 2-3 weeks. No ring. Goes right to voicemail. Tried rebooting. Tried Safe Mode. Tried turning off Wi-Fi. Nothing works. No ring tone. Goes right to voicemail. Do not disturb is off. Forwarding is off. Night mode is off. T-Mobile 1st-level phone support person had no ideas. He transferred me to higher-level support. They had me reset the network settings on my phone. Then they tried to reset my call forwarding feature using ##004# dial code, but kept getting "invalid MMI code." Then he had me do a long pattern reset **61*18056377243**10# which did reset my call forwarding, and recovered my ring tone, but the ring time was too short, so he increased the ring time to 25 seconds using code **61*18056377243**25#  ----- and now everything is back to normal.

Apparently, an Android / Samsung / TMobile automatic software update 2-3 weeks ago messed some things up.