This article at the PFF website caught my attention. In the article, Adam Thierer, in reflecting on the recent Gmail outage, applies the ideas of this article from Wired to telecom. The telecom network has been engineered (at high cost) to 99.999% (i.e., "five nines") reliability; the question is whether this quality level is anywhere close to what is demanded by the market.
In some sense, we have a test case in that we are willing to consume different feature sets in telecom at different prices. Wireline telephony is the most reliable with the highest voice quality at price $x, mobile telephony is less reliable and has lower voice quality (with mobility) and is offered at price $y and VoIP has probably less reliability and lower quality than either at a lower price ($z). As a note, I don't think it is fair to say that $z=0 because we do pay for internet access and the computer that runs the VoIP software.
So is there only a marginal demand for quality, which might partially explain why wireline access lines are on the decline? Or is it strictly due to the substitution of mobile for wireline access?