The whole point of hiding support phone numbers is to try to keep users from calling, because each call costs money. The usual effect is to diminish goodwill and ensure that they’ll be even more annoyed when they do find the number and call. On the other hand, if the 800 number is in plain sight—perhaps even on every page—somehow knowing that they can call if they want to is often enough to keep people looking for the information on the site longer, increasing the chances that they’ll solve the problem themselves.
