Protocol modules are used by captagent to process specific protocol pipelines. Protocol modules are loaded at startup by the captagent.xml general configuration.

<configuration name="modules.conf" description="Modules">
	    <modules>
	
		...
		<load module="protocol_sip" register="local"/>
		<load module="protocol_rtcp" register="local"/>		                                  
		...
		
	    </modules>
</configuration>

Note: This list is probably incomplete by the time you read it. You can get all functions available here: protocol_sip.c