Hello, There might be a spelling error below, you probably mean: "$xavu(_tps_=>contact_host) = "2.2.2.2"; And this works fine but obviously sets the contact_host to 2.2.2.2 across both interfaces, I ideally want it to change between 10.10.10.10 and 2.2.2.2." Not sure if I understand your question correctly. You could just conditionally set the contact host to the different values, depending on your configuration logic. Cheers, Henning -- Henning Westerholt - https://skalatan.de/blog/ Kamailio services - https://gilawa.com<https://gilawa.com/> From: sr-users &lt;sr-users-bounces(a)lists.kamailio.org&gt; On Behalf Of Jonathan Hunter Sent: Friday, December 3, 2021 8:57 AM To: Kamailio (SER) - Users Mailing List &lt;sr-users(a)lists.kamailio.org&gt; Subject: [SR-Users] topos xavu_field_contact_host kamailio 5.5 Hi All, I was wondering if anyone can help, and advise me if I am missing something when using topos in an environment where I have more than one interface for kamailio. Essentially I would like to set the contact_host to 2 different values depending on the flow of the SIP requests, as we have a private LAN interconnect for example 10.10.10.10, and a public interconnect using 2.2.2.2 (for example). I notice there is xavu for A-side contact and B-side contact, but what about just the contact host? As I have set for example; modparam("topos", "xavu_cfg", "_tps_") modparam("topos", "xavu_field_contact_host", "contact_host") ... $xavu(_tps_=>contact_host) = "2.2.2.2"; And this works fine but obviously sets the contact_host to 8.8.8.8 across both interfaces, I ideally want it to change between 10.10.10.10 and 2.2.2.2. How can I set more than one contact_host $xavu that topos can use? As my understanding is you can only set $xavu once, so is there another way to manipulate the contact_host on requests coming in and out on different interfaces? I assume I am missing something? :) Thanks in advance Jon Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for Windows