Since v3.0.0, Kamailio's support for handling SIP over TLS is a matter of loading the TLS module, a completely refactored TLS implementation.
Unlike for v1.x.y, where it was needed to recompile everything, core and modules, to get support for TLS, starting with v3.0.0 that became a straightforward mechanism, suitable for demands of handling large volume of data over signaling channel, like for Instant Messaging and Presence.
Built on the new more scalable and flexible core architected for v3.0, one Kamailio instance can handle now many ten thousands of active connections (one test case here).
The README of TLS module is now a complete tutorial about how to tune the parameters for TLS configuration. You can read it at: