Hello, tell them to read again the RFC3261, respectively the Via grammar: Via = ( "Via" / "v" ) HCOLON via-parm *(COMMA via-parm) via-parm = sent-protocol LWS sent-by *( SEMI via-params ) via-params = via-ttl / via-maddr / via-received / via-branch / via-extension via-ttl = "ttl" EQUAL ttl via-maddr = "maddr" EQUAL host via-received = "received" EQUAL (IPv4address / IPv6address) via-branch = "branch" EQUAL token via-extension = generic-param The generic-param, defined also in the same RFC, is anything in the form 'name=value'. The 'i' parameter is the tcp/tls connection id to speed up routing or responses. Out of curiosity because I know it is there for long time and nobody complained about it so far, I looked at branch 0.9.0 (ser times) and it is there: - https://github.com/kamailio/kamailio/blob/rel_0_9_0/msg_translator.c#L1325 That branch is from year 2004 and the code can be even older. There is no option to disable adding it, you will have to patch the code in src/core/msg_translator.c - the if block at line 2857. Cheers, Daniel On 05.04.17 12:04, DanB wrote: -- Daniel-Constantin Mierla www.twitter.com/miconda -- www.linkedin.com/in/miconda Kamailio Advanced Training - May 22-24 (USA) - www.asipto.com Kamailio World Conference - May 8-10, 2017 - www.kamailioworld.com