This is a very old question that has been answered many times. However, since it's so hard to find things on this forum, you're forgiven.
Instead of routing inbound calls to Google Chat, which is what your OBi device uses to connect to the service, get a free, inbound NY State telephone number from Callcentric. Sign up for CC's E911 service (it's cheap).
Add and verify that number to your Google Voice account as a forwarding number, and add a check-mark next to it, on this page:
https://www.google.com/voice#phonesRemove the check-mark next to Chat. Provision the Callcentric number on your OBi: log into the OBiTALK portal page, click one of your SPs, and then scroll down to the bottom of the page and click the "Next" button to select Callcentric as the provider, and enter your Callcentric number's SIP user name and password, and select that SP as the one to receive inbound calls. Also, select it as the SP to use for E911 calls.
Inbound calls to your GV number will now be routed through your CC number, which will add CNAM. Call 933 from your OBi-attached phone to test that 911 service is working. The automated voice will read out a different telephone number -- this is normal. All that matters is that it reads out your street address.