Update/ additional data:
I have just tried a softphone, and it did the same thing (one-way audio)
Then I tried the softphone using the direct dial CC phone number, and it worked properly.
Tried my Obi SP1 using the direct CC number, and it also worked.
So the problem now is isolated to when the call goes thru my GV number and forwarded to CC. Whether the call goes to a softphone or to my Obi unit, If GV handles the call and sends it to CC, I get one-way audio. If the Obi or the softphone gets the call straight thru CC and does not come from GV number, it gets 2-way audio. But I have GV on SP2 using the Gtalk/chat and that is still working.
This now appears to be mainly a GV issue. And possibly a GV-forwarded-to-SIP/DID to be more specific.
I am now out of leads myself...