Vb.net 在active directory中编辑电话号码

我能够按照下面的代码从Active Directory检索用户信息。但我如何授权current编辑和更新他们的电话号码？此应用程序正在SharePoint server中运行

Dim netBIOSname As String = Me.Page.User.Identity.Name
Dim sAMAccountName As String = netBIOSname.Substring(netBIOSname.LastIndexOf("\"c) + 1)
txtuser.Text = sAMAccountName
Try
    Dim userName As String = txtuser.Text
    Dim searcher As New DirectoryServices.DirectorySearcher( _
       "(mailNickname=" + userName + ")")
    Dim result As DirectoryServices.SearchResult = searcher.FindOne()
    If result Is Nothing Then
        Label2.Text = "Unable to find user: " + userName
    Else
        Dim employee As DirectoryServices.DirectoryEntry = result.GetDirectoryEntry()
        txtfirstname.Text = employee.Properties("givenName").Value.ToString()
        txtlastname.Text = employee.Properties("sn").Value.ToString()
        txtfullname.Text = employee.Properties("cn").Value.ToString()
        txtempid.Text = employee.Properties("physicalDeliveryOfficeName").Value.ToString()
        txttitle.Text = employee.Properties("title").Value.ToString()
        txttele.Text = employee.Properties("telephoneNumber").Value.ToString()
        txtdept.Text = employee.Properties("department").Value.ToString()
        txtmobile.Text = employee.Properties("mobile").Value.ToString()
        Dim ManagerName As String = employee.Properties("manager").Value.ToString()
        ManagerName = ManagerName.Substring(3, ManagerName.IndexOf(",") - 3)
        Dim searchMgr As New DirectoryServices.DirectorySearcher("(cn=" + ManagerName + ")")
        Dim resultMgr As DirectoryServices.SearchResult = searchMgr.FindOne()
        If resultMgr Is Nothing Then
            Label2.Text = "Unable to find Manager: " + ManagerName
        Else
            Dim empManager As DirectoryServices.DirectoryEntry = resultMgr.GetDirectoryEntry()
            searchMgr.Dispose()
            resultMgr = Nothing
            empManager.Close()
        End If
        searcher.Dispose()
        result = Nothing
        employee.Close()
    End If


Catch ex As Exception
    Label2.Text = "The following error occurred: " + ex.Message.ToString()
End Try