IP Trunk Fallback
IP Office 3.1 introduces support for IP Trunk Fallback. When setting up a call over an IP trunk, if the remote PBX fails to respond within an adjustable timeout (default 5 seconds), the IP Office can reroute the call attempt.
IP trunk fallback is performed separately for each call. The use of fallback for a preceding call does not alter the routing attempted for any following call to the same IP trunk.
Within a Small Community Network, calls to remote user are automatically routed to an IP trunk setup for connections to the appropriate remote IP Office. If the remote IP Office doesn't respond to the call attempt with the set timeout, the call is rerouted.
First the call is rerouted to any other trunk with the same outgoing group. If this is the case, that trunk must be able to route calls to the correct remote IP Office without any further dialing. This would typically require the fallback trunk to be a private leased line.
If the call is still not connected, an attempt is made to reroute the call via LCR short code matching of the original dialed number.
- his later method is the preferred case as the LCR short code matching allows number manipulation to make the outgoing dialing suitable for rerouting across the PSTN. To make this the preferred case, the IP trunk should be put into its own unique Outgoing Trunk Group ID.
In cases where the call is routed to the IP trunk by a Least Cost Route in the first place, the timeout used for IP trunk fallback is the Timeout defined for the current tab of the LCR form being used. A value of 0 disables IP trunk fallback.
Setting the Default IP Trunk Fallback Timeout
The default timeout for IP trunk fallback is 5 seconds. This timeout can be changed for specific IP trunks and or all IP trunks. The required timeout is set through the Source Numbers tab of the NoUser user. The entry or entries take the form H323SetupTimerNoLCR line_number timeout where the line_number should be ALL for all IP trunks or the specific Line Number used for the IP trunk on its Line configuration tab, and the timeout is set in seconds.