Outlook - Apply VBA code to appointments when selected but not opened

[gmayor]

The following should work

Sub InsertConfCallInfo()
Dim myItem As AppointmentItem
    On Error Resume Next
    Select Case Outlook.Application.ActiveWindow.Class
        Case olInspector
            Set myItem = ActiveInspector.currentItem
        Case olExplorer
            Set myItem = Application.ActiveExplorer.Selection.Item(1)
    End Select
    myItem.Location = "CALL: (866) 555-1212 / CODE: 9854101812"
    myItem.Save
lbl_Exit:
    Set myItem = Nothing
    Exit Sub
End Sub