But Sky's takeup of FTTC customers most be miniscule and certainly not enough to max out any exchange capacity.
We seem to have got into a disagreement when we are in fact in agreement.
The red herring was the introduction of ADSLx noise margin settings. You then took that and seemed to criticise all BT Wholesale based services based on the woeful Sky Connect and comparing it with Sky LLU.
Back to FTTC

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In terms of backhaul capacity I think the jury will be out for a considerable time. BT Wholesale clearly have a huge backbone capability, though whether it will be enough (as it is now) for the Olympics and 80Mbps connections during them isn't known by me. Then there is the feed from the exchange into that backbone.
Sky will be dependent on their feed from exchanges into their own network. As has been said, they have a good reputation on that. Though if any shortfall shows up during the Olympics I doubt if they can react as quickly as BTW. Having a "miniscule" takeup so far, (no doubt increasing rapidly), is in my opinion more likely to cause exchange problems than a safety margin. BTW install extra backhaul at an exchange before enabling it. Do Sky?
Maybe they do. We already know they don't automatically accept FTTC at all BTW-enabled ones. So far I've thought that would be to do with the type of DSLAM and the installation of ther GEA links, but maybe backhaul capacity is another upgrade they do beforehand.
BT Retail will be dependent on both the BTW backbone and their own MSIL capacity. That will be interesting to see during the Olympics, when compared with Sky, TT and the premium BTW-based ISPs.
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