Most of my players have my MSN, and my PM Inbox is always open on the forums.
Only the staff has my personal home # and cell #, in the case of major emergencies(for example, I was out to dinner with my family and my co-admin called with a server-wide issue(unable to restart)).
I've got digital phone, so it doesn't cost me a dime to call my staff(1 on the east coast US, 1 in central US, and 1 on the west coast of Canada).