Hi Austin, Kamailio should be pretty fast on these things. Here are things which you can check: * Increase number of TCP workers/make sure you are using async TCP. * Use in-memory store for your registrations, not DB ones (at least dump async your contacts in DB). * Make sure you allow enough files to be opened in case of TCP connections (I suspect this is your issue there). Regarding performance tests, not sure if you saw already these links: http://www.kamailio.org/docs/openser-performance-tests/ https://sip-router.org/wiki/performance/v3.0-capacity Hope these help! DanB