w84no1
OBiTALK Service->Enable = uncheck both check marks
This will shut the OBitalk service. However I think it will also shut you off the OBi portal service, any auto provisioning you may want to enable, remote firmware updates from OBi, ect...
Another way is just to block all calls from OBis. Obis seem to start with 2 and 3, using a variation of what RonR suggested you could setup a comprehensive call block.
Voice Services -> OBiTALK Service -> InboundCallRoute : <- insert rule here
P2P1 is probably means peer to peer. Which is how the OBi is setup on their network.
Edit: Clarify