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When the Peeredge Switch receives a SIP Invite from an upstream PSTN Service Provider in the Dallas datacenter it will match data center, the switch matches an Originating Customer Trunk Group based on the called party number in the SIP Invite. The The Softswitch will then build builds a list of all active trunk members configured in this Trunk Group for Dallas and then forward forwards the SIP Invite to the trunk member (i.e. SBC/PBX) based on the configured Call Distribution.
If there are no active trunk members in Dallas or no responses from the active trunk members in Dallas then , the Softswitch will forward forwards the SIP Invite to the Ashburn Softswitch, which builds a list of all active trunk members configured for Ashburn. The Ashburn Softswitch will then forward forwards the SIP Invite based on the configured Call Distribution. The The same call failover routing behavior will occur occurs if the SIP Invite is first received in the Ashburn datacenterdata center. An active trunk member is any customer SBC/PBX that responds to SIP Option messages. If SIP Option messages (Trunk Monitoring) is are not configured on the Originating Customer Trunk Group, then all trunk members in the trunk group are considered active.
PSTN Outbound (Terminating Customer) Failover Routing
When the Peeredge Switch receives a SIP Invite from a customer in the Dallas datacenter it will match data center, it matches a Terminating Customer Trunk Group based on the customer customer’s SBC/PBX IP Address, Port, and Protocol (UDP, TCP, TLS). If no match is found, the Softswitch will respond responds with a SIP 401 with a WWW-Authenticate header to allow for SIP Registration-based authentication. Once Once authenticated, the Softswitch will route routes the SIP Invite to all configured PSTN Provider Trunk Groups configured in Dallas.
In the unlikely event that all configured PSTN Provider Trunk Groups configured in Dallas are down then , the SIP Invite will be is forwarded to the Ashburn datacenter, and the Ashburn Softswitch will route routes the SIP Invite to all configured PSTN Provider Trunk Groups configured in Ashburn. The same call failover routing behavior will occur occurs if the SIP Invite is first received in the Ashburn datacenterdata center.