You cannot. The only way to use a device with Google Voice is with an OBI and if you want to use GV as a gateway then you can create a SIP Trunk between the PBX and the OBI and setup the routing on the OBI.
You cannot. The only way to use a device with Google Voice is with an OBI and if you want to use GV as a gateway then you can create a SIP Trunk between the PBX and the OBI and setup the routing on the OBI.