dewey152 Said:
"iPhone 7 keeps ringing on incoming calls: [...]The problem is that the ringer keeps ringing on an incoming call even after I pick up the call.[...]"
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Troubleshooting Continuous Rings:
Reset the iPhone:
One though would be to just set-up it your iPhone up anew, as if you were to sell it. The phone number would remain. Perform as instructed here, including the backup creation, and then iCloud logout: Use this Link: What to do Before you Sell, Give Away, or Trade in your iPhone, iPad, or iPod touch - Apple Support