Our SIP providers is saying we should configure our UC520 to communicate with their proxy sip devices for more security between us and them. can anyone give me an ideas of how to configure ALG from UC520 to a SIP proxy. The current setup works fine but our access lists on the SIP lines are preventing some hosts to connect to us so we had to remove the ACLs reducing security. So in place of that we like to implement ALG with UC520. Is this even possible?