39 C.F.R. § 6.4
For regularly scheduled meetings of the Board, members are expected to attend in person. Unless prohibited by law or by these bylaws, however, a member of the Board, under exceptional circumstances, may participate in a meeting of the Board by conference telephone, video conference, or similar communications equipment which enables all persons participating in the meeting to hear each other and which permits full compliance with the provisions of these bylaws concerning public observation of meetings. Attendance at a meeting by this method constitutes presence at the meeting and a member of the Board may be paid for his or her participation provided such meeting addresses substantive, as opposed to procedural or administrative, matters on which the Board has decision making authority.
39 C.F.R. §6.4