I reported this to Google Voice engineering staff yesterday afternoon. They have identified the problem and they are working with Poly to resolve it.
To be clear: no action on your part is necessary nor will fix it at this time. This outage is a good reminder that nobody should depend on Google Voice as their sole source of telephone service, and you can configure your OBiTALK device to use one or more other service providers, such as Callcentric or voip.ms
I'm sorry, but I don't have any status update to report, since my Google contacts are off for the weekend. Nonetheless, it's safe to assume that they are working on it, and I will pass along any news I can get.