I thought calling with google voice was the point of the device!
I tried a bluetooth headset and the quality was awful. One reason I'm considering OBI is because I expect the quality of the calls will be better on a hard phone.
I don't need OBI to make wifi calls on my smarphone; the GV app takes care of that.
I guess it is hard to explain to me the potential advantages of OBI if you don't Know what I would like to do.
Basically, I'm trying to overhaul my phone system at the office. I run three land lines; two direct office lines and a main office line. I'm considering forwarding the mainline to a GV account that rings the two direct lines, which are in turn forwarded to individual GV accounts. That way, If the main line rings, and I am on the phone, my partner can take the call. Both of us can access the main GV account to review, notate, and forward voicemails and review logs of missed calls ect.