Hello, I don’t think you can put a host name in the contact header. I have already tried and I didn’t receive the reinvites. ________________________________ De : sr-users &lt;sr-users-bounces(a)lists.kamailio.org&gt; de la part de Mack Hendricks &lt;mack(a)goflyball.com&gt; Envoyé : mardi, avril 7, 2020 8:29 AM À : Kamailio (SER) - Users Mailing List Objet : [SR-Users] Substitution of Contact Header Hey All, I always have issues with substituting out header values. I’ve tried subst and subst_hf. Here is the value that I want to change out: Contact: <sip:52.41.52.34:5060;line=sr-h06Cy7RYRFkYacM0a7epa7sVa7sVRcNCW7IbaGZ9RGlC> And this is what I want it to be Contact: <sip:1313717555@jump.dsiprouter.net;line=sr-h06Cy7RYRFkYacM0a7epa7sVa7sVRcNCW7IbaGZ9RGlC> I’m using this subst('/^Contact: <sip:(.*);(.*)>$/Contact: <sip:1313717555@jump.dsiprouter.net;\2>\r/ig’); And it doesn’t work, but putting into a online regular expression tester it looks good as shown below. Any ideas? [cid:71DF5B41-831E-48A2-9F06-D3D3F84F1CEF]