you can't have 2 Obi's use the same google voice account, only one will work.
It could be said that "If they both call out and the outgoing caller id is for the same google voice account then the hard part is done". But with the same account on both devices, which ever one registers with google last is the one that will receive the calls. So if one ever reboots, for what ever reason, it will likely take over.
You should set up one as the main Obi and fork calls to the other. And have the second one dial through the first one using single stage dialing.
Set Obi A to fork calls to Obi B.
On Obi A (the one that currently receives calls)
set your inbound call route for sp1 to {ph,pp(ob200xxxxxx)} where 200xxxxxx is the Obi number for Obi B.
This will ring the phone on Obi A and also fork the call to Obi B.
after the above changes, if both devices currently make calls, then both will also receive calls.
As for setting up single stage dialing on the second device, that will require more in depth settings. i will get the info and come back.
You can make these changes from Obitalk.
From the dashboard, click on the device you want to edit
enter the Obi expert configuration
Voice Service -> SP1 Service -> X_InboundCallRoute = {ph,pp(ob200xxxxxx)}
