Haven't checked, but it may not apply to businesses - I'd be surprised if a company could opt all of its phone numbers out of all potential vendor calls.
We found a great remedy: answer their calls with a soundboard. We like the Mr. Rogers soundboard [1]. Its fun, harmless, and they'll stop calling very quickly.
[1] http://www.ebaumsworld.com/soundboards/play/1866/ (warning, autoplays some sounds)
Of course it applies to outgoing calls from businesses, as that's the entire point of the law.