We started using freeswitch for one of our products. We use esl to control calls. I am trying to come up with numbers to do capacity planning. I ran my tests on 8 core cpu 16 GB Ram server. This is on ubuntu 14.04 linux (kernel 3.13) distro on amazon web services. I used sipp to do load tests. I used freeswitch's external profile (single profile only) as I will have to deal with third party SIP trunk providers and G711 is the codec I used. When I executed 500 concurrent calls by creating 500 calls at the same time, things work fine. I see linux's load staying close to 3. When I do 1000 concurrent calls by creating 1000 calls at the same time, linux's load shoots to 75 and sometimes reaching 100. Earlier, I did the same test on 4 core 8 GB server, load shot up to 75 for 500 concurrent calls. When I searched for freeswitch installation on aws, I read that timer configuration and low latency kernel changes are recommended. But It also says it is not needed for 3.x kernel. So, Is this needed to extract good performance from hardware on aws ? Instead of adding hardware blindly, I would like to figure out is there any other way I can profile this and understand the relationship between hardware and concurrent calls number. Thanks, Niranjan KL