For me, the OBiTALK Service has been very unstable the past 24 hours. Sometimes the OBi's can't connect to the server, other times calls fail with 404, and other times it's just flaky in general. When it's working, I don't find any problem pressing 1 to continue the call to the OBi's PHONE Port.
Google Voice and VoIP services on the OBi's has remained solid for me.