iambrent ,
Welcome
I also have an Obi100 set up for my parents which worked perfectly until this past week. Now it is showing as offline in the OBi dashboard and it is unable to place or receive OBi-to-OBi calls, and it is unable to complete a call to the Echo Test. However, incoming and outgoing calls on SP1 using Google Voice still connect just fine.
Two conclusions come to mind from your test.
1) OBiTALK service was down. (as proven by your test)
2) ATA functional as per your GV test
Analysis:
OBiTALK is down more often than we may realize. We can not expect 100% up time on this service. A strategy to overcome the reliance on the OBiTALK service is to have other voice services configured on the ATA such as GV, a sip account (commercial or free such as sip2sip), direct ip to ip from your OBi to your parents OBi. The last option is the most direct method avoiding any 3rd party points of failure of the voice service providers. Down side is that it requires port forwarding or to be connected VPN style (router<->router).