Hello Guys. Looks like the default value for sip_warning_noisy_feedback on the cookbooks 4.0.x looks wrong: It says by default it's enabled, I run couple of test on my kamailio 4.3.4 (x86_64/linux) and I had the header present only when I specifically declared it to 1 https://www.kamailio.org/wiki/cookbooks/4.0.x/core#sip_warning_noisy_feedba… Disclaimer: I didn't check the source code yet Thanks Alessio