Hans-Werner,
This all is probably true if the objective is to provide the best possible IP service. If you apply other requirements, like integration of the current telephony system, or, more accurately, evolve the telephony system, in the telephony company mindset, to something that also supports data, video, and things like that, things look different.
I can't disagree with this but I think it misses the point, which is an issue which should be orthogonal to ATM. I think it may very well be the case that it is not possible to build a really large, reliable Internet without really large IP routers. I.e. it is not ATM that is the problem, it is this picture of a stinking big ATM switch milking hoards of teeny little routers the may not provide a scalable Internet. If you want to build a big Internet you may very well need big routers, it matters little whether they're plugged into an ATM switch or directly into a TDM (with the proviso that the router interfaces to plug into the former are going to be a technology generation or two more complex than the latter, no matter what you do). We know we want to build a big Internet. Yet somehow the big routers one may absolutely require to do this became (a) uninteresting as topics of research and development, (b) not well-understood as a necessity because of the big-switch-little-router picture, even though this may have no relationship to working reality, and (c) even if none of the above, the big-router development may still be constrained by the view that a big router is useless unless it is equipped with big ATM interfaces, even though the latter may turn out to be harder to build than the former and we're really getting the cart before the horse. So the end result is, no big routers, even though there is apparently little about ATM which eliminates the need for big routers if you want a big Internet. And all ATM has really managed to deliver so far is obfuscation of the issues, putting us in a holding pattern where we're just waiting to see what breaks but not doing that much about it. So I can't deny that the integration thing is attactive (I personally don't dislike ATM either, to tell the truth), but I really do think that somehow the priorities got all mixed up somewhere along the way. Instead of primarily worrying about advancing the state of the art for each of the services people actually want to buy, using whatever delivery technology was mature enough to accomodate this reliably, we've somehow instead made the integration the holy grail and have just forgotten to even care about whether there's anything left worth integrating by the time we find it.
Then again, so far I see little activity in the context of service integration. More ATM as a level-2 replacement for data networking. Which brings us back to your comments, as in such an environment the benefit is more marginal (e.g., ATM may still have multiple service qualities before it is being implemented in an IP(+) substrate). Oh well. If there were just concerted goals.
I would suggest that the reason you don't see a lot of activity in the context of service integration is that (at least at the phone company I know a little about) the guys that run the voice network are about the most pragmatic people in the place, which means they make sure their vendors deliver the big iron switches when they need them, and that they've got enough fiber in the ground to connect them together, so that even if it turns out that ATM isn't as great a thing as it was thought it might be, you still won't get a lot of fast busy signals. I wish one could say the same about the Internet. Dennis Ferguson