With multiple GV accounts you have no way to know which line is ringing and contacts often don't show up on caller id. I have no idea if someone is calling via biz line or personal line thru GV and adding a contact pulls names from all accounts on phone instead of only the selected GV account. So many other limitations for seemingly no real reason. Why!?? GV is a killer service and this could be a killer app but it seems intentionally crippled.