Exec Script in the background, don't wait till it finishes

Hi there, i'm currently working on a socket project. It consists of two scripts. The first script (socket1.php) creates a socket on a specified port and waits for a client to connect. If a client connects, they exchange some informations, including a random created port. Next, the first script calls the second script (socket2.php) with the just created port number as a parameter. Now here is the problem: it all works fine, but the client can't send a quit message to socket1 because socket1.php waits until socket2.php is finished. socket2.php is working properly, and if i connect to the new socket and quit the connection, socket1 is working again. All i need socket1 to do is to continue working independant of socket2. I tried everything, from shell_exec to pcntl_exec, nothing seems to work. regards, Kai