Public Class Form1
 
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles MyBase.Load
        Me.TextBox1.Text = Me.GetPhoneNumberParameter
    End Sub
 
    Private Function GetPhoneNumberParameter() As String
        For Each arg As String In Environment.GetCommandLineArgs
            If arg.ToLower.StartsWith("-p:") Or arg.ToLower.StartsWith("/p:") _
              Then
                Return arg.Split(":")(1)
            End If
        Next
        Return String.Empty
    End Function
 
End Class