did someone work already on the following feature? It should be relatively easy to do via ESL: let's say our FreeSWITCH server is a part of a redundant cluster, and it should stop accepting new calls if its PSTN gateway is down. Ideally, it would stop responding on OPTIONS pings, so that its upstream neighbors recognize that this node is not good for sending calls. So, the solution should define dependencies between gateways (ideally, not only SIP gateways, but other endpoint types too), like: if gateway X is down for more than 10 seconds, shut down gateways Y and Z. If X is up for more than 5 seconds, bring up Y and Z. In a more scalable approach, you would trigger the change if less than a certain percentage in a set of gateways is down.