diff --git a/lib/tasks/dial.js b/lib/tasks/dial.js
index 2fa32534..4b4415f4 100644
--- a/lib/tasks/dial.js
+++ b/lib/tasks/dial.js
@@ -400,15 +400,19 @@ class TaskDial extends Task {
     let fqdn;
 
     if (!sbcAddress) throw new Error('no SBC found for outbound call');
+    this.headers = {
+      'X-Account-Sid': cs.accountSid,
+      ...(req && req.has('X-CID') && {'X-CID': req.get('X-CID')}),
+      ...(req && req.has('P-Asserted-Identity') && {'P-Asserted-Identity': req.get('P-Asserted-Identity')}),
+      // Put headers at the end to make sure opt.headers override all default behavior.
+      ...this.headers
+    };
+
     const opts = {
-      headers: req && req.has('X-CID') ? Object.assign(this.headers, {'X-CID': req.get('X-CID')}) : this.headers,
+      headers: this.headers,
       proxy: `sip:${sbcAddress}`,
       callingNumber: this.callerId || req.callingNumber
     };
-    opts.headers = {
-      ...opts.headers,
-      'X-Account-Sid': cs.accountSid
-    };
 
     const t = this.target.find((t) => t.type === 'teams');
     if (t) {