Worlds better than 20/1!
There was a time when I'd have killed - OK, maybe not
quite that far
- for 20/1
My phone line is about 5km long, the "natural" sync was typically 1.5Mbps down and 400kbps up - however the one "good" thing about the line is that it is largely underground so there wasn't much diurnal variation in the noise figure. Thus, with very careful tweaking of the target SNRM, I was able to get about 3Mbps down.
Prior to that I had ISDN because the fastest a modem would go was about 20kbps. I suspect the line was marginal for ISDN even and some "hand picking" of pairs was involved.
Mind you I counted myself lucky to get that much out of ADSL - there are still plenty of people in the UK who have local loops much longer than mine.