When you are sending an UPDATE to a Carrier from one SBC Oracle, and recieve the replay «405 Method Not Allowed», is because the Carrier didn´t support UPDATE, you can modify for RE-INVITE, adding parameter «update-interworking» OPTIONS inside CORE SIP-INTERFACE configuration:
sip-interface
realm-id CORE_CARRIER
description Core Carrier
sip-port
address 10.10.10.1
allow-anonymous agents-only
options update-interworking