I have the same symptom although I'm not sure it's the same as yours or not. When I call a number using GV using a SIP phone connected to my Obi 200 (even if I'm dialing another GV number), with the latest software 5989EX, I noticed that instead of going to voicemail, my SIP phone will go to fast busy. And when it does, the line GV is on (SP1) seems to hang. If I pick up anything else (analog, SIP, etc.) and try to dial out using the GV SP1, it will say that the line is unavailable (I think I saw a 503 error?). Then about a minute or two later, on the logs, I will see a connection reset on the GV line where it re-establishes the TCP connection to GV and then GV works again until we try to call another line that gets forwarded to voicemail. When the line is hung, all LEDs are lit.