Same thing in France, France telecom was nationally owned until the early 2000's. Now it still maintains the local loop but is forced through regulations to share copper pairs to any other ISP. That way concurrent isps only have to setup a backbone.
I use sonic.net here in SF and I think they work in a similar way by piggybacking on the ATT local loop. I wonder if there is any local law that forces ATT to co-operate in that case.
It's not a local law, it's FCC regulation. AT&T is the ILEC and Sonic the CLEC. This is part of the reason AT&T wants to move everyone to U-Verse---it's not subject to the same regulation as regular phone lines (being FTTN instead of service via central office, as in regular DSL).
I use sonic.net here in SF and I think they work in a similar way by piggybacking on the ATT local loop. I wonder if there is any local law that forces ATT to co-operate in that case.