Telco guy here, similar story. Our standard procedure dictates who is on the crisis call, with increasingly high ranks being sucked in as the incident escalates

Telco guy here, similar story. Our standard procedure dictates who is on the crisis call, with increasingly high ranks being sucked in as the incident escalates the severity scale by meeting objective criteria - for the highest levels of outage (think "no more phone service in the whole country" or "ministry of defence lost all its fiber links"), it can theoretically mean waking up the CEO in the middle of the night. Representatives of involved teams may come in and out of the call but usually stay on to maintain liaison.