For inbound calls, the SIP call can be received on a UDP/TCP/TLS socket.

To determine the identity of the SIP entity from which the call originated, the SIP routing system compares the source IP address of the SIP request. The SIP routing system compares the source IP address with the IP addresses or Resolved IP addresses for the FQDNs associated with the provisioned SIP Server Configurations, looking for a match.

If the SIP call matches with a provisioned Server Configuration, the routing system iterates over the provisioned Server Flows associated with the server configuration, looking for a match. See the Server flow matching section.

If the SIP call is not associated with any server configuration, the call is rejected unless it matches a provisioned subscriber flow. See the Subscriber Flow Matching section.