I did some modification while you were doing your latest post.
If you want calls to come in to GV from your historic phone number, why not port your number to GV?
If you port to
voip.ms, why not receive the calls from
voip.ms without those calls involving GV?
Those are the common ways to do what I think you are looking to do.
So here is my suggestion:
Use OBitalk.
Set up GV on SP2. Tell OBiTalk that most outgoing calls should go to SP2 by default.
Set up
VOIP.ms on SP1. Have 911 calls go to SP2. If Google is down some day or if you want the outgoing caller ID to have your old landline number, prefix your call with **1
I expect that while
VOIP.ms is not free, that it is very reasonable. I know the Anveo rates, and I expect
VOIP.ms is competitive. If it seems that it is not pretty cheap, ask them. You may have misunderstood their pricing.
Which is SP1 and which is SP2 is arbitrary. See
http://www.obihai.com/FAQ.php and the links in the left column to get info on setting up GV.