diff --git a/lib/call-session.js b/lib/call-session.js
index b4c895d..6eb7df1 100644
--- a/lib/call-session.js
+++ b/lib/call-session.js
@@ -1038,8 +1038,9 @@ Duration=${payload.duration} `
         const response = await this.uac.request({
           method: 'REFER',
           headers: {
-            'Refer-To': stringifyUri(uri),
-            'Referred-By': stringifyUri(u),
+            // Make sure the uri is protected by <> if uri is complex form
+            'Refer-To': `<${stringifyUri(uri)}>`,
+            'Referred-By': `<${stringifyUri(u)}>`,
             ...customHeaders
           }
         });
diff --git a/package-lock.json b/package-lock.json
index 95fd014..401192e 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -20,7 +20,7 @@
         "cidr-matcher": "^2.1.1",
         "debug": "^4.3.4",
         "drachtio-fn-b2b-sugar": "^0.1.0",
-        "drachtio-srf": "^4.5.31",
+        "drachtio-srf": "^4.5.35",
         "express": "^4.19.2",
         "pino": "^8.20.0",
         "sdp-transform": "^2.14.2"
@@ -1707,9 +1707,9 @@
       }
     },
     "node_modules/drachtio-srf": {
-      "version": "4.5.31",
-      "resolved": "https://registry.npmjs.org/drachtio-srf/-/drachtio-srf-4.5.31.tgz",
-      "integrity": "sha512-/M4J8h2aqHtMXWr8/UHngKQsY9sQQxjdd23jDTSpNVpCwgZ2/xZFhbg/B/UCjrarSRzbyDCvuluOAtaPRSw7Hw==",
+      "version": "4.5.35",
+      "resolved": "https://registry.npmjs.org/drachtio-srf/-/drachtio-srf-4.5.35.tgz",
+      "integrity": "sha512-4LOb6Rjie8OHpUdqjhU8Zpkc6rquA4LBLqjH419bAJFKG/XqMYeIqPo7PF3GLy5TGghrx487RTP0DmFbH5B01g==",
       "dependencies": {
         "debug": "^3.2.7",
         "delegates": "^0.1.0",
@@ -6659,9 +6659,9 @@
       "requires": {}
     },
     "drachtio-srf": {
-      "version": "4.5.31",
-      "resolved": "https://registry.npmjs.org/drachtio-srf/-/drachtio-srf-4.5.31.tgz",
-      "integrity": "sha512-/M4J8h2aqHtMXWr8/UHngKQsY9sQQxjdd23jDTSpNVpCwgZ2/xZFhbg/B/UCjrarSRzbyDCvuluOAtaPRSw7Hw==",
+      "version": "4.5.35",
+      "resolved": "https://registry.npmjs.org/drachtio-srf/-/drachtio-srf-4.5.35.tgz",
+      "integrity": "sha512-4LOb6Rjie8OHpUdqjhU8Zpkc6rquA4LBLqjH419bAJFKG/XqMYeIqPo7PF3GLy5TGghrx487RTP0DmFbH5B01g==",
       "requires": {
         "debug": "^3.2.7",
         "delegates": "^0.1.0",
diff --git a/package.json b/package.json
index 3a105a0..e260c7f 100644
--- a/package.json
+++ b/package.json
@@ -38,7 +38,7 @@
     "cidr-matcher": "^2.1.1",
     "debug": "^4.3.4",
     "drachtio-fn-b2b-sugar": "^0.1.0",
-    "drachtio-srf": "^4.5.31",
+    "drachtio-srf": "^4.5.35",
     "express": "^4.19.2",
     "pino": "^8.20.0",
     "sdp-transform": "^2.14.2"