Hi:
Yes, this is exactly how I, and many others, use their OBi devices with Google Voice and Callcentric.
For example:
Let's assume that you used the OBiTALK portal to configure Google Voice (actually Google Chat) on your OBi's SP1.
Get a free or paid inbound phone number from Callcentric (doesn't matter, since you don't have to give out this number). Subscribe to Callcentric's E911 service.
Refer to the attached screenshot below.
Using the OBiTALK portal page, click the SP2, then, on the next page, scroll all the way down to the bottom of the page, and click "OBiTALK Compatible Service Providers". On the next page, select Callcentric, and OBiTALK will properly configure SP2 with optimal values for Callcentric -- all you need to add is your CC 1777xxxxxxx SIP account number and SIP password. Check the box to ring on inbound calls, but don't check the box to make this the primary line for outgoing calls. Check the box to use this SP for 911 service.
Call your Callcentric's real telephone number (not the 1777 number) from some other phone to confirm that it works and you can answer it on the OBi-attached phone.
Log into your Google Voice account and go to the Settings page, Phones tab:
https://www.google.com/voice#phonesRemove the check mark to the left of "Google Chat". This will disable inbound call routing via Chat to your OBi, but outbound calling will still work.
Scroll down and click the "Add another phone" link, and add and verify your CC phone number. Test your setup. Outbound calls will use Google Chat by default, and inbound calls will use Callcentric by default, and 911 will automatically route out via SP2/CC.
Test emergency calling by calling 933 from your OBi-attached phone. You should hear a machine voice read back your 911 street address and it will tell you that it's set up properly. Ignore the bogus telephone number it reports you are using; this is a feature designed to give the E911 call center a way to reach you if the call gets disconnected.
Enjoy the benefits of GV + CC!
