Not a direct question on kamailio, but on rtpengine, so feel free to ignore :) 

I have a farm of rtpengine servers , supporting our set of kamailio's. 

On recent decent hardware (hp dl360 gen9/10 servers), I typically push my systems upto 2500 channels per machine. Then I tend to see the load of the machine go up in a logarithmic manner. E.g. a load of 3 supports 2500 channels, but when its at 3000 channels, load can be at 8. etc.

I have the kernel module running, and I have a good impression it's being used too. No transcoding is going on, no recording, ... I've tried on different OS'es, different network cards, and I always end up at that 2500 channels +-. 

Is that what I can expect from rtpengine? Or am I really overlooking something? What numbers do you push out of your systems? 

kind regards and happy 2020!