I don't feel that IMs are an appropriate medium for support. It is largely an unsupported opinion that I formed because of experiences in the past with people being quite bothersome. You would ignore them if they weren't customers, but they are, so you don't really have the option.
As far as a 1-800 number, only if there is someone to answer the phone 24/7, and that person isn't your g/f
-- HW