Recently, at a Radio Shack store at the telephone accessories
> section, I noticed that telephone extension cords were available in
> lengths up to 25 feet (but I didn't notice any that were longer).
> Is that because 25 feet is the longest you can go before there's a
> significant loss of signal strength?
I think the limit is about 18,000 feet. Then you might have trouble carrying DSL over it.
Of course, a crummy extension cord with badly crimped connections that are coming apart can mess up your connection even if it's two inches long, but so long as it's well made, don't worry about it.
R's,
John