Consider taking the off-hours calls yourself. Even let the late night calls ring through into your bedroom. This may seem a step too far, but it will demonstrate the need for this level of support. In time you will decide to hire out this service. A support page that is well organized and easy to navigate is a real plus.
Many visitors prefer to find answers themselves, rather than make a call or send an email.
Given even one repeat, get it up there. If you offer a variety of products, visitors may become confused. Set up a page of suggestions, and comparisons if appropriate. And include that 800 number with good answers when the phone is picked up. Many are turning against the US Post Office.