Imports System.Management

Public Function ModemsConnected() As String
        Dim modems As String = ""
        Try
            Dim searcher As New ManagementObjectSearcher(
                "root\CIMV2",
                "SELECT * FROM Win32_POTSModem")

            For Each queryObj As ManagementObject In searcher.Get()
                If queryObj("Status") = "OK" Then
                    modems = modems & (queryObj("AttachedTo") & " - " & queryObj("Description") & "***")
                End If
            Next
        Catch err As ManagementException
            MessageBox.Show("Ocorreu um erro ao consultar os dados do WMI: " & err.Message)
            Return ""
        End Try
        Return modems

    End Function
'-----------------------------------------------------------------------
FORM LOAD:

  Try

            Dim ports() As String
            ports = Split(ModemsConnected(), "***")

            For i As Integer = 0 To ports.Length - 2

                ComboBox1.Items.Add(ports(i))

            Next

        Catch ex As Exception
            'MsgBox(ex.Message)
        End Try

'---------------------------------------------------------------------------
1 LABEL PORTNAME = LABEL1.TEXT

  Private Sub ComboBox1_SelectedValueChanged(sender As Object, e As EventArgs) Handles ComboBox1.SelectedValueChanged
        Label1.Text = Trim(Mid(ComboBox1.Text, 1, 5))
    End Sub