I have had an Obihai ATA phone that used a Google Voice phone number for a few years.
Google is ending support for ATA boxes from May 15th 2014. Their logic is that they no longer support SIP technologies.
September, 2014 UPDATE Scratch that. Google Voice is now to be officially supported on Obihai ATA (analog telephone adapter) boxes.
OK, So my Obihai account managers sent me an email to do something so that I can keep my Google Voice number as a DID (Direct In Dial) number.
They tried to push me to a service provided by ANVEO. No problem, but not my first choice. The offer was for about $40 p.a. and was a reasonable offer. I do have an ANVEO SIP account already. But I ended up transferring my Google Voice phone number to VoIP.MS
VoIP.MS provide a good system and I have experimented with their services before.
The porting of my Google Voice number to VoIP.ms took about 5 days. I had to pay Google a small transfer fee.
The new DID line hosted now at VoIP.MS is working fine with no issues.