[After composing this post, I found the answer in this forum. I'm going ahead with the post to help others find the quick fix.]
Two years ago, I set up my OBi200 with a Google Voice account and Internet service from Comcast/Xfinity. I just replaced Xfinity cable to GoNetspeed fiber. All of household devices (Macs, iPhones, iPad, Echo Dots) are again working via Ethernet or Wi-Fi.
The OBi200's Ethernet and phone connections have not changed. My phone gets a dial tone, but when I dial a number, I get an immediate voice response: 3 beeps + "The number you dialed [insert number] has not received a response from the service provider." Calls to my Google Voice number go to voice mail.
Quick fix: Unplug the OBi200, wait a moment, and restore power. When the 3 "dancing" lights on the OBi200 settle down, phone service has been restored.
I still haven't fixed my error. Maybe it's not in OBi200.
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