Thanks, @Arizona480, for your speedy, helpful response to my post.
I completed the setup of my Google Voice account, providing my iPhone number. When I had my daughter call the GV number, it rang on both my iPhone and the OBi200's phone.
I visited the Google Voice Settings > Calls > Incoming calls panel and disabled "Call forwarding" to my iPhone – see the attached screenshot. Now incoming calls ring only on the OBi200's phone.
Success!!!