I liked it best when I could call and have my question answered while I was in the midst of the problem and not have to wait for "office" hours. I often work on family history very late at night.
Messaging didn't work as well either as it was not immediate and it turned out I had not given him the information he needed to respond to my question.
When I have been able to talk to someone on the phone they have been able to tell what was needed to help me out. Problem solved immediately and it was fun to talk to someone in a completely different time zone/country.