No, not quite. The ISPs using IPConnect link directly to the ATM Network yes, but not SPECIFICALLY for DSL, IPDirect is Telkom's service for ATM Connectivity. Thus, IPDirect = high speed leased lines, normally 2MB/s and upwards. Each ATM Link carries a high number of different "cells", and Telkom decides which Cells the other provider's link must and must not get. It's like a massive frame-relay leased line network basically, just using fiber and higher throughput rates (and that's putting it very simple).
That's also a fancy way for IS to make another couple of thousand out of end-users because you MUST sign a contract, and you MUST take their routers (for the static IPs), so that you cannot see the VPN Configurations that is made active on those routers. If those settings did come out, it could be a potential security risk on IS' side.
Again, I stand correct above and below, but unless your VPI / VPC Settings are different from Telkom, you are using Telkom's ATM Network (or rather, Telkom's BRAS) to terminate your connection (ala PPPoE Session), and not another provider. If the settings are the same, you are essentially still terminating on Telkom's Network, and the 1st tier in question (UUNet / IS) is using some form of "traffic redirecting / routing" via a dedicated ATM Circuit or VPN to re-route the traffic over their own network, and thus creating the "effect" of having the DSL terminate on their own equipment.
Again, please, I'm not 100% on this, I MAY VERY WELL BE WRONG! In all honesty, I think ALL other 1st Tier ISPs do NOT have a ATM Link directly to all of Telkom's DSLAMs. They merely have one ATM Link from site 1 to site 2 and re-route all the traffic through that onto their own network (It is even possible that Telkom's Radius Servers can assign UUNet IP Addresses to UUNet's ADSL Customers). Therefore, they also get congested MUCH quicker than Telkom does, because it is one or at the most I'd say 3 34MB ATM Circuits to cary just how many 512kb sessions????
The same can be said about Sentech the same can be said about WDS. A single (5 at most) high speed links, expected to provide a entire country of service... It simply does not work like that. You create a single bottle neck on your network, and all your customers are forced through that bottle neck.