Hi:
When you go through the initial OBiTALK device setup pages on your OBiTALK dashboard, it will ask you which Service Provider (SP1-SP4) you want to use for E911 calls. You'll click the box for SP2. Once you do that, the device's dial plan (digit maps) will be altered such that, when the digits 911 are detected, it will route the call out via SP2.
Note that it's unclear if you can still buy the E911 for OBi service from Anveo. If not, I suggest using Callcentric, instead.