[Users] ACK is answered after the INVITE. But ACK arrived first!

Hi all Im in trouble with this problem: I have a Openser the connect to a carrier. I need that this proxy answer the messages in order that it receive. In my situation, other device one hope behind it, sends an ACK and, miliseconds after, it sends an INVITE to change the session. The server where the Openser is installed receive the ACK first than INVITE, but it ALWAYS forward this INVITE first. This way, I cant connect my proxy to the carrier. I need to know how I can change this behavior: the SIP proxy needs to send the ACK first. First in, first out..... Anybody knows how to do it? Thanks for any suggest Bruno Machado --------------------------------- Abra sua conta no Yahoo! Mail - 1GB de espaço, alertas de e-mail no celular e anti-spam realmente eficaz.