Hello, why are you sleeping for 1s in the loop? This will cause Kamailio to block processing. I also do not see any stop condition on the loop, so it will loop until the limit. Cheers, Henning -- Henning Westerholt – https://skalatan.de/blog/ Kamailio services – https://gilawa.com<https://gilawa.com/> From: sr-users &lt;sr-users-bounces(a)lists.kamailio.org&gt; On Behalf Of Giovanni Jose Sent: Tuesday, March 29, 2022 9:46 PM To: sr-users(a)lists.kamailio.org Subject: [SR-Users] More than TCP 800 concurrent calls, slows Kamailio (LUA FILE API REQUESTS) Hello Guys I am having this issue where kamailio is receiving requests from SIPp (we are currently testing the platform and doing QA) but if we do more than 800 concurrent calls kamailio starts failing and slowing the requests, The scenario is the following: I am sending 5000 calls at 100 CPS on TCP and I am having this route in the configuration file: # Handle the calls to api route[CALL_API] { xlog("L_NOTICE"," Call request $var(call_request) method: $rm \n"); $var(loop_true)=1; while ($var(loop_true)) { if(!lua_run("call_request","$var(call_request)","$sht(token=>new_token)")) { xlog("L_NOTICE", "SCRIPT: failed to execute lua function!\n"); } if ($var(loop_true)){ sleep("1"); } } xlog("L_NOTICE", "SCRIPT: Sucess to execute lua function!\n"); } So I am executing a LUA script for the requests and the API response will tell the destination of the call. At 800 concurrent calls, I can notice SLOWLINESS in the SIPp testing tool, and then I will start receiving 408 timeouts. This sounds like a load issue or something because I believe there's a time that it's been added every time we hit the backend and wait for the response. any help will be appreciated Regards Gio