Hi jimates,
This sounds good. And I have thought about it.
Let me recap my understanding of what you are suggesting:
1. Have two Google Voice numbers - one for each cell phone.
2. When owner of Cell phone 1 calls from Ph1, GV1 (Google Voice 1) is used to call out.
3. When cell phone 1 rings and the phone is home, Ph1 rings - due to Obibt connection.
4. When owner of Cell phone 2 calls using Ph2, GV2 is used to call out.
5. When Cell phone 2 rings and the phone is home, Ph2 rings - due to Obibt connection.
6. When GV1 rings, Ph1 rings, and so does the Cell phone 1. And the same for GV2, Ph2 and Cell phone 2.
7. And then setup VM such that GV becomes VM recipient - these are AT&T phones.
Is the above how you envision it?
The only issue in this, is that the outbound number is different from the cell phone. It is the GV number.
But otherwise it is a scenario worth doing - at least until GV is free it does not cost any extra.
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Edit:
Responding to your edit - It sounds like you are describing a situation where ObiBT is not needed. If the cell phone is not answered, it will ring GV number before going to VM. Right?