My phone rings once and goes to voicemail when I have the wifi on. I do not have the do not disturb on. If I turn the wifi off it works. This is not a new phone, it just started to happen yesterday.
iPhone 7 Plus, iOS 10.3.2
Reset the iPhone.
Hold the volume-down and on/off buttons together for about 10 seconds until the Apple logo appears.
If that does not solve it, ask your cellular carrier if there's some issue on their side.
Try changing the setting at:
Settings > Phone > Wi-Fi Calling
I only suggest this because of your observation of the ringing correlating to Wi-Fi being on or off.
Thanks, but it didn't work
My phone is only ringing once, and goes to voicemail
