Mad respect for salespeople doing cold calling. Failure Rate: 99%. Still worth investing the time in for those 1% of new customers.
Just don't be too annoying from what's in your control. And expect to be butchered verbally. Happens! In the worst possible stress-loaded moment, your little advert might be the tiny bit of information overflow that will make people explode...
Though this should be less likely to happen on the web. I mean who replies to "spam ad" mails? One click, delete, case finished.
So I'd say cold calling is particularly well suited for the web. It's not even close as intrusive as going from door to door.