diff --git a/lib/call-session.js b/lib/call-session.js
index 6c67110..bc5b217 100644
--- a/lib/call-session.js
+++ b/lib/call-session.js
@@ -57,6 +57,11 @@ class CallSession extends Emitter {
       if (this.req.locals.application_sid) {
         Object.assign(headers, {'X-Application-Sid': this.req.locals.application_sid});
       }
+      else if (this.req.authorization &&
+        this.req.authorization.grant &&
+        this.req.authorization.grant.application_sid) {
+        Object.assign(headers, {'X-Application-Sid': this.req.authorization.grant.application_sid});
+      }
 
       debug(`sending INVITE to ${proxy} with ${uri}`);
       const {uas, uac} = await this.srf.createB2BUA(this.req, this.res, uri, {