Yes.
Sign into Gmail, not GV. Click your chat avatar on the left side of the page, midway down. It's the generic head and shoulders icon, or a photo you uploaded. It will pop open the Hangouts settings box. Click the small link at the bottom that says "Revert to old chat". Now, make your phone call. You can go back to using Hangouts after you're done doing this one call.
Don't forget to add a check mark next to the Chat destination in GV Settings, so that you will receive inbound calls on your OBi device.