Introduction
With Global Dial Plan Replication (GDPR), independent Unified CM clusters can share dial plan elements such as URIs, +E.164 numbers, enterprise numbers, +E.164 patterns, enterprise patterns, and PSTN failover numbers using the Intercluster Lookup Service (ILS). All local dial plan information advertised by a Unified CM cluster is advertised as part of a single GDPR catalog. Reachability for advertised dial plan elements is achieved by advertising a location attribute (SIP route string) together
with each GDPR catalog.
For every DN in Unified CM, the enterprise or +E.164 alternate number can be selected to be advertised as the PSTN failover number. On remote clusters this PSTN failover number is used for PSTN failover for calls to the +E.164 alternate number, enterprise alternate number, or URIs. PSTN failover is triggered if a call to any GDPR learned destination fails with cause codes other than unallocated number, user busy, normal call clearing, destination out of order, or service not available. The PSTN failover
number is also used for Automated Alternate Routing (AAR) in case of call admission control failure.
For calls to the PSTN failover number, the AAR CSS of the calling device is used on the remote cluster.
PSTN Failover number is advertised as PSTN failover for
+E.164 Alternate Number
Enterprise Alternate Number
URIs
PSTN Failover number is
+E.164 Alernate number (typical)
or
Enterprise Alternate Number
Using +E.164 Alternate number as PSTN failover number enables very simple PSTN failover handling on receiving clusters.
Related Information
