I'm wondering if I setup the GV under SP1 and ASTERISK under SP2. While the phone connected to the OBI is talking to someone via a trunk (i.e. COMNET) in Asterisk. Is it still possible that if someone can still make a connection to the OBI's GV via the Asterisk?
In fact I am using the setup that you described. Since Asterisk accepts multiple calls, you are allowed to make phone call via Comnet or GV, depending on the availability of the trunks provided.