SMS using GPRS and VB.Net Hanging after Message

<br />
'This is for Connecting Port<br />
<pre lang="vb">private sub OpenPort()
OpenPort("COM5",11520,8,1,300,300)
End Sub</pre><br />
<br />
<pre>
private sub SendMessage()
Dim X As String = ClsMSg.ExecuteATCommand(Port, "AT", 300)
If X.Contains("OK") Then
    X = ClsMSg.ExecuteATCommand(Port, "AT+CMGF=1", 300)
    If X.Contains("OK") Then
        Dim PhoneNo As String = "0559963424"
        Dim command As [String] = "AT+CMGS=""" & PhoneNo & """"
        X = ClsMSg.ExecuteATCommand(Port, command, 300)
        If X.Contains(">") Then
            Dim Cmd As String = "this is a test message " + Char.ConvertFromUtf32(26) & vbCr
            X = ClsMSg.ExecuteATCommand(Port, Cmd & vbCr, 300)
        End If
    End If
End If

end sub

Public Function OpenPort(ByVal StrPortName As String, ByVal p_baudRate As Integer, ByVal p_Databits As Int16, ByVal p_ReadTimeOut As Integer, ByVal p_WriteTimeout As Integer, ByRef ConnStatus As String) As SerialPort
        Try
            With Port
                .PortName = StrPortName
                .BaudRate = p_baudRate
                .DataBits = p_Databits
                .StopBits = StopBits.One
                .Parity = Parity.None
                .ReadTimeout = p_ReadTimeOut
                .WriteTimeout = p_WriteTimeout
                .Encoding = Encoding.GetEncoding("iso-8859-1")
                AddHandler Port.DataReceived, AddressOf Port_DataReceived
                .Open()
                .DtrEnable = True
                .RtsEnable = True

                ConnStatus = "Y"
                Return Port
            End With
        Catch ex As Exception
            ConnStatus = ex.Message
        End Try
        Return Port
    End Function

'this codes for stop connection
    Public Sub ClosePort(ByVal port As SerialPort)
        Try
            port.Close()
            RemoveHandler port.DataReceived, AddressOf port_DataReceived
            port = Nothing
            ClsComm.ShowNotification("SMS CENTER", "SMS Service Stopped", ToolTipIcon.Info)
        Catch ex As Exception
            ClsComm.ShowNotification("SMS CENTER", "Failed to Stopp SMS Service ", ToolTipIcon.Error)
        End Try
    End Sub

<pre lang="vb">Public Sub Port_DataReceived(ByVal sender As Object, ByVal e As SerialDataReceivedEventArgs)
    Try
        If e.EventType = SerialData.Chars Then
            ReceiveNow.[Set]()
        End If
    Catch ex As Exception
        Throw ex
    End Try
End Sub</pre><br />
<br />
    Public Function ExecuteATCommand(ByVal Port As SerialPort, ByVal Scommand As String, Optional ByVal ResponseTimeOut As Integer = 300) As String<br />
        Try<br />
<br />
            Port.DiscardOutBuffer()<br />
            Port.DiscardInBuffer()<br />
            ReceiveNow.Reset()<br />
<br />
            Port.Write(Scommand & vbCr)<br />
            Threading.Thread.Sleep(300)<br />
            Dim Input As String = ReadResponse(Port, ResponseTimeOut)<br />
<br />
            If (Input.Length = 0) OrElse ((Not Input.EndsWith(vbCr & vbLf & "> ")) AndAlso (Not Input.EndsWith(vbCr & vbLf & "OK" & vbCr & vbLf))) Then<br />
                Return "ERROR"<br />
            Else<br />
                Return Input<br />
            End If<br />
        Catch ex As Exception<br />
            Return "ERROR"<br />
        End Try<br />
    End Function<br />
    Public Function ReadResponse(ByVal Port As SerialPort, ByVal TimeOut As Integer) As String<br />
        Dim Buffer As String = String.Empty<br />
        Dim ErrMsg As String = ""<br />
        Try<br />
            Do<br />
                If ReceiveNow.WaitOne(TimeOut, False) Then<br />
                    Dim T As String = Port.ReadExisting<br />
                    Buffer += T<br />
                Else<br />
                    If Buffer.Length > 0 Then<br />
                        ErrMsg = "Incompleted Response."<br />
                    Else<br />
                        ErrMsg = "No Data Received."<br />
                    End If<br />
                    Exit Do<br />
                End If<br />
            Loop While Not Buffer.EndsWith(vbCr & vbLf & "OK" & vbCr & vbLf) AndAlso Not Buffer.EndsWith(vbCr & vbLf & "> ") AndAlso Not Buffer.EndsWith(vbCr & vbLf & "ERROR" & vbCr & vbLf)<br />
<br />
            If ErrMsg.Length > 0 Then<br />
                Buffer = "ERROR"<br />
            End If<br />
<br />
        Catch ex As Exception<br />
            Return "ERROR"<br />
        End Try<br />
        Return Buffer<br />
    End Function<br />
<br />
<br />
<br />
<br />
after i sending message using this code its the x returns sometimes error and some times its hang in the message portion with ">" if i stop port and start again the message is sending. i tried in the hyper terminal its Sending Message but the last line not getting response<br />
<br />
AT<br />
OK<br />
AT+CMGF=1<br />
OK<br />
AT+CMGW="+85291234567"<br />
> A simple demo of SMS text messaging.<br />
+CMGW: 1<br />
<br />
OK<br />
AT+CMSS=1<br />
<br />
after this portion hanging but message is sending<br />
<br />
And also Iam Using IMPULSE USB GPRS MODEM. <br />
please help me