Kamailio， how to append params to Contact in INVITE

Question

i try save the original contact, remove it and append to new one in the kamailio.cfg.

$var(orig_contact) = $(hdr(Contact)[*]);
xlog("L_INFO", "Before removing Contact: $hdr(Contact)\n");
remove_hf("Contact");
xlog("L_INFO", "After removing Contact: $hdr(Contact)\n");
$var(new_contact) = $var(contact) + ";param=value";
append_hf("Contact: $var(new_contact)\r\n");

the kamailio log show the Contact Before/After removing is the same, that means the it not work. Could anyone tell me how to make it?

Answer 1

Official kamailio answer that this is against RFC.

You can change it. But if you are using RTPPROXY or RTPENGINE you have change it AFTER rtpproxy/rtpengine loop, because it takes contact from original message.

So,

fix_nated_contact/add_contact_alias

Will just put it back.

Try without NAT to see that.