Well, sort of. Depends on what country you are in, too. In AU/NZ at least (and I am simplifying) you have the last mile, the trunks between exchanges, the hand

Well, sort of. Depends on what country you are in, too. In AU/NZ at least (and I am simplifying) you have the last mile, the trunks between exchanges, the handover points between big exchanges and ISP POPs, and finally you have the ISP upstreams - any of which might be a bottleneck if sufficient traffic is generated. In AU/NZ (and much of the rest of the world) you have local peering exchanges etc, but ISPs also have this cost for "upstream", which is money they have to pay to their friendly international cable monopoly to get bits from faraway places. These backhaul links are not normally configured to handle all users running at full rate. That would be expensive, and silly. In the fixed line world, you might observe "congestion", but it the root cause is usually "oversubscription". Everyone oversubscribes backhaul and upstream, the question is how much you can get away with. The reward for guessing lower than your competitors is lower costs (or being able to defer an upgrade cycle). The penalty for guessing way too low is churn. I say "guess" because even though telcos tend to have good models of user behaviour, user behaviour can change very quickly (from a telco's POV) when new services come on line. Such as online video...