For telco at least, the problem boils down to graceful random backoff at all interconnection points. Without that, you die miserably. So, for example, you can b

For telco at least, the problem boils down to graceful random backoff at all interconnection points. Without that, you die miserably. So, for example, you can boot up your class 5 softswitch, but it will be unhappy if no sooner than you do that than the access network equipment starts spamming it with connection attempts (and, equally, it tries connecting trunks to the rest of the pstn). So you need things like congestion control, randomized backoff, etc. Telco switches can do this. An amusing aside is that IP telephony sometimes gets into a mess here, as SIP sends a 503 with a retry after prompt to the client, but its not always randomized, so you can get these waves of barbarians at the gate, who all go away, and then all come back again exactly 180 seconds later...