Comment Spanning Trees (Score 2) 205
Haven't the telcos ever heard of "Lowest Cost Spanning Trees?". This is what's done in internet routers to prevent exactly the kinds of infinite loops causing the problems there.
Spanning trees still provide the carriers with the best available pricing for a given set of call end points over the available routers, but also ensure that infinite loops don't occur within the network, thus providing proper connectivity to the end user.