I found a way that seems to work--at least till May. I got a free phone number from ipkall. I signed up with FreeCall and gave them 10 euros. I don't think I would have had to pay anything for incoming calls. I also tried iptel for free, but there was too big a delay in call forwarding from GV. So far the GV forwarding to Freecall seems to happen within a single ring time.
I set my obi202 (SP1) to use GV. (Note: I ported my old landline number to GV.) I set up Freecall on SP3 (SP2 was already taken with my attempt to use iptel). I set up talkatone on the iphone to also use the same GV number/account that I had just assigned to the obi202. Doing that disabled receiving incoming calls on the SP1. I set up GV to forward calls to Google Chat (now connected to talkatone on the iphone). I also set GV to forward calls to the ipkall/FreeCall phone number. I set the obi to SP1 for all outgoing calls. (Also I set up 911 calling using Anveo for $12/year on SP4.) (I also set Expert Configuration>Service Providers>ITSP C>DTMFMethod to "InBand" ,made sure Profile C was used by SP3, so that faxing over ipkall/FreeCall worked much better)
Now when I call my old landline number Google Chat rings the iphone, and the GV forwarding to the ipkall/FreeCall number rings my home phone. When I answer either one, the other stops ringing (with a small delay). When I make a call from either phone, it uses GV outbound to make a free call.
So everything is great until May. Then I am going to look at what obihai and talkatone have available. If nothing free, I will use FreeCall or some other SIP provider. Incidentally, while FreeCall looked good on the web site, in reality it is not so cheap, and I can't find a way to do caller-id spoofing so my GV number is always sent to the called party--like happens now with GV making the call. I read in various web sites about LocalPhone (cheap), Future Nine, and Callcentric's 500 minute plan. I also read about
Ring.To.
Hope this helps someone.