Out of pure self-interest, I checked out my phone service provider on the web
and found a little info on the web.
To summarize what I found, BellSouth, at least, has NO touchtone ("90#") feature
that gives a caller access to a private phone account. So BellSouth customers
using their home phones are safe even if they do cooperate with the "dial 90#"
request.
The articles seem to acknowledge the possibility that some PBX systems used by
BUSINESSES might have such a feature, or at least features that might be misused
in this way.
That's all for what it's worth. The following articles pretty much cover all of
what I found:
http://www.bellsouth.com/sc/newsroom/PR-798-3.htm
http://www.bellsouth.com/tn/news/pr000043.htm
I also found the following writeup on some other phone scams:
http://www.bellsouth.com/workathome/infodigest/lookout.html
