Genesys Cloud implements call draining as a best practice procedure for safely removing external trunks from service. Call draining prevents new calls from being routed to a designated trunk while allowing existing active calls to complete their normal lifecycle before the trunk is taken offline. To enable this feature, administrators with Telephony > Plugin > All permissions access the trunk configuration through Menu > Digital and Telephony > Telephony > Trunks, select the External Trunks tab, choose the target trunk, navigate to External Trunk Configuration > General, toggle the Call Draining switch to Enabled, and save the configuration. This functionality ensures service continuity and prevents call interruption during trunk maintenance or decommissioning operations.