Same problem here. I submitted a ticket to support.
First call, 9:42pm eastern last night. Googled for info, found to change routing to "{}" to block all calls. Tried, but as reported doesn't seem to stick. What i observed was that the first time i changed and rebooted, it reverted. Second time, it seemed to stick. But then my Google Voice inbound wasn't working, so I rebooted again. (Perhaps not necessary, still wasn't working, so I made an outbound call, which worked, and then inbound worked again.) Checked the setting, and it had reverted. Repeated the process, and it took two reboots again, for the setting to stick.
But it somehow reverted during the night, because at 3:17am, I was awakened byt he phone ringing, then again a minute later, and again a minute after that. At that point, I unplugged my phone from the OBI.
Plugged the phone back in this morning and it immediate rang again. The call history shows ~50 calls overnight. What the hell? They continue to come roughly every 10 minutes according to the call history--I had to unplug my phone again, because of it.
Waiting for a response from support. Good news is, if it's not an isolated incident, that ought to mean they will make a priority of fixing it.
Even if it's some weird backend system problem, I want a permanent fix to be able to disable the OBITalk calls at my device. have no use for the service, and am not interest in being awoken in the middle of the night again, because they had some kind of backend system meltdown.
How does one access OBI expert?