Question: What aspect of NAT traversal is NOT addressed by the "Outbound" methodology defined in RFC 5626 for use with the Session Initiation Protocol (SIP)?
Option 1: Establishment of initial outbound connections through NAT devices
Option 2: Routing of inbound responses and mid-dialog requests after connection establishment
Option 3: Maintenance of NAT traversal flows using keep-alive messages
Option 4: Deployment scenarios for multiple UE registrations
Explanation: The "Outbound" methodology, as described, focuses on establishing flows for inbound dialog initiating requests and maintaining these flows. However, it does not provide a solution for the routing of responses back to the UE (inbound responses) or handling mid-dialog requests that may also need to traverse the NAT, highlighting a limitation in its approach to comprehensive NAT traversal for SIP communications.