I paid for an extra service plan with obihai, and they never responded to a single service request. This company has been acquired by polycom, which isn’t the same company that used to be either. These are actually good SIP adapters, but if they still work with Google Voice today they are probably at end of life. Google Voice unfortunately does strange things so that most SIP adapters will not work. These days it’s a much better idea to use a SIP povider like Flowroute, and I ported my Google Voice number there.
What kind of “strange things” are you referring to? My obi200 has worked just fine since I’ve had it.