Utl-tcp Connection - Oracle Generic Network Error?

I have a client program that needs to communicate with another server program. My client program is implemented in PL/SQL using utl_tcp running on Oracle 9 while the server program is a 3rd party software running on Windows server 2003.

Basically my client program needs to send a request to the server, waits for the response (wait for the incoming string which ended /w chr(3) ) and then acknowledge (sending chr(6) ).

My problem is that if I wait for the chr(3) and then acknowledge. My send routine (l_sent := utl_tcp.write_text (g_conn, p_content) will raise a Oracle generic network error. It seems like the connection is closed. I checked /w the vendor and they said it might be I am taking too long to response ( I question timeout is the problem). I have also attempted to change my read routine from read_line to read_raw but it only make things worst. I cannot even read the complete string. At least with read_line, I can read back the entire string.

My current work around is to send out the ack before I receive the chr(3) (which is not recommended by our vendor).