Over and over again I'd have the same exchange with ISP representatives:
Me: I just want to double-check one thing? It says here that you offer [IMAP e-mail/10 megs of Web space/local-call access from Stafford County/wireless broadband/24-7 tech support/some random other feature]. But there's no mention of this on your site.
ISP: Oh, yeah, we haven't updated it yet.
If you want to compete with the name-brand guys, make it easy for a visitor to see why you're different from them. Few customers enjoy playing 20 Questions on the phone; if they don't see a feature they need advertised, they're going to click on to the next provider's site.
3) Make it as easy as possible for potential customers to see where your
services are available.
If you offer DSL or cable -- both services that may not available universally -- provide an easy-to-find form on your site at which people can check to see if service is available at their home, then give them an answer in real-time, not in an e-mail the next day. (Verizon gets this right; a "can I get DSL?" form is in the middle of its www.verizon.net home page, and you don't even need to type in a street address, just a phone number.)
Promise visitors that you won't use the contact info they volunteer to nag them afterwards, and mean it.
4) Throw a bone to the press and provide a clearly labeled contact for PR queries.
Way too often, I had to e-mail the questionnaire to a generic "webmaster@" or "sales@" account, because no other contact was listed online. At that point, it was entirely up to chance whether somebody would read the message, then act on it.
In a few examples, I did find a PR-contact e-mail on the site, but nobody was actually reading this catchall "pr@" address. That's not good either. If you're going to do that sort of thing, have a warm body assigned to check that inbox every workday.