A Survivable Media Gateway (SMG) will attempt to register with an Alternate Call Server in the event of the Primary Call Server not being reachable, eg, an equipment or WAN outage. Ideally, an SMG will have some local trunking. See also Survivable Media Gateways.
Additional MGC Settings for Geographical Redundant Systems
1 In Element Manager, navigate to Media Gateways, and select the MGC card (loop/shelf).
2 In the Embedded LAN section, check Geographical Redunancy.
3 Fill in the Alternate call server (ELAN) IP addresse(s) as appropriate, and Save.
The Geographic redundancy timer timer sets how long the MGC will wait (after losing connection to the primary caller server) before trying to register with an alternate call server. Switching between Primary and Alternate Call Servers requires the MGC(s) to re-boot!