diff --git a/lib/call-session.js b/lib/call-session.js
index 23060ef..e636863 100644
--- a/lib/call-session.js
+++ b/lib/call-session.js
@@ -380,6 +380,7 @@ class CallSession extends Emitter {
               '-X-Preferred-From-User',
               'X-Preferred-From-Host',
               '-X-Jambonz-FS-UUID',
+              '-X-Voip-Carrier-Sid',
             ],
             proxyResponseHeaders: [
               'all',