I'm going to assume you mean Google Voice and not Obitalk. It's highly unlikely anyone is robocalling the Obitalk network of 9-digit numbers.
If there was some way to add the NOMOROBO phone number as a linked number to Google Voice, you could accommodate simultaneous ring easily. However, there's no way to validate a phone number that you can't answer directly.
SO, you can either pay for a SIP service to provide you a DID you could forward to NOMOROBO and link that to your GV number...
Or maybe something more complicated. Which Obihai device do you own?