I'm getting this same problem. It's every so and so. See the attached screen shot for error history. Anyone find a fix for this? Very frustrating and dangerous due to 911 unavailability:
"Service Offline Alert – Obi Device is Not Registered
Your voice service is not registering. This could be due to a temporary
service disruption or an incorrect login credential.
In most cases, reconfiguring the voice service with the proper login credential
will resolve the issue."