Signaling and Media Mode

In order to use AnyFirewall™ Engine to send SIP messages and establish the connection to the SIP server, it is necessary to replace the SIP stack’s socket functions with those of AnyFirewall™ Engine. The actual steps to achieve this differ depending on the SIP stack. Some SIP stacks allow replacing the lower layer functions and even provide an API for that; in other cases the source code of the SIP stack must be modified and socket calls must be replaced with the functions from the connection management and data transfer APIs of AnyFirewall™ Engine, such as Connect, Send, and Receive.

Figure 5: Signaling and Media Mode

For the connection to a server, the API function Connect is used. It takes the IP, port, and protocol (UDP, TCP, TLS) of the SIP server as parameter and connects using the most suitable transport. It is also possible to traverse HTTP proxies in this mode.