Child pages
  • SipXbridge and Interoperating with High Availability ITSP Nodes

Versions Compared


  • This line was added.
  • This line was removed.
  • Formatting was changed.


Ace Innovative has recently introduced a high availability service and has begun migrating most of their clients to this ITSP node named There are actually two target nodes behind - ( ) and ( is provisioned in the address field  (PSTN gateway address in the Devices->Gateways->SIP trunk menu) when the SIP trunk is defined. The way Ace has defined the service is that all traffic goes through the primary csp1 nodeand the backup csp2 node is used only when csp1 is unavailable. In the above diagram, Ace Innovative has defined a NAPTR record for called That NAPTR record is then used to query the SRV records - two are returned. The target node is the record with the lower priority (10) and Sipxbridge should register to this node. Sipxbridge queries for the NAPTR and SRV records correctly - the issue is that Sipxbridge prior to 17.10 does not process the SRV records correctly, and registers the trunk to about 50 percent of the time. sipXbridge in 17.10 and later now handles ITSP connections with SRV records.

The good news is that on a busy Sipxcom system, there is no impact when the SIP trunk registers to Sipxbridge always sends a keep-alive UDP packet every 20 seconds to regardless of whether the SIP trunks registers to csp1 or csp2. If there are incoming PSTN calls that arrive within the 10 minute SIP trunk registration window, then the invites will continue to be delivered from the primary csp1 node. The firewall state for csp1 is maintained by the 20-second Sipx keep-alive packet, so the incoming call successfully traverses the firewall to the Sipxcom server.