I configured SP1 for GV, as per the blog post instructions. Configured SP3 as the SIP proxy, also as per instructions...with one difference: I could not, no matter what I tried, get the SIP phone to ring using {ph1,SP3(abc@local_client)} as the inbound call route on SP1. Not sure what 'local_client' is supposed to route to, anyway.
So I substituted it with the SIP target of the IP phone itself: {ph1, SP3(abc@xxx.xxx.xxx.xxx:pppp)}, where 'x' is the IP dotted-quad and 'p' is the SIP port (50640 in this case). That works. Sort of. Now, the phone will ring when the GV account number is called, along with any POTS device plugged into phone port 1 of the Obi, but while the hard phone has the expected two-way audio after call setup, the IP phone has only one way audio; namely, the other party can hear me talking, but I cannot hear them. Call setup proceeds flawlessly, but the RTP data doesn't seem to be reaching the IP phone.
I have tried it with and without symmetric RTP enabled at either or both ends (Obi/IP phone). No dice. The phone in question is a Grandstream GXV3140. Outbound proxy on the phone is set to 192.168.10.1:5062, which is SP2 on the Obi. SIP server on the phone is set to the same.
Any suggestions?