# How H.324M functions work

For each function except h324Initialize, the host application passes an msphd parameter that is the handle to a MUX endpoint. The MSPP service returns this handle to the application when the MUX endpoint is created with mspCreateEndpoint. The handle is used to determine the channel with which a function is associated.

The H.324M Middleware is asynchronous. No H.324M Middleware functions block while waiting for a response from the CG board or from the remote 3G-324M video terminal. Information from the CG board or the remote 3G-324M video terminal is sent to the application using its Natural Access event queue.