diff --git a/lib/session/call-session.js b/lib/session/call-session.js
index c410830b..8d5c2f92 100644
--- a/lib/session/call-session.js
+++ b/lib/session/call-session.js
@@ -1302,7 +1302,8 @@ class CallSession extends Emitter {
       this.dlg = await this.srf.createUAS(this.req, this.res, {
         headers: {
           'X-Trace-ID': this.req.locals.traceId,
-          'X-Call-Sid': this.req.locals.callSid
+          'X-Call-Sid': this.req.locals.callSid,
+          ...(this.applicationSid && {'X-Application-Sid': this.applicationSid})
         },
         localSdp: this.ep.local.sdp
       });
diff --git a/lib/session/siprec-call-session.js b/lib/session/siprec-call-session.js
index 34a5fedf..e734fe70 100644
--- a/lib/session/siprec-call-session.js
+++ b/lib/session/siprec-call-session.js
@@ -36,7 +36,8 @@ class SipRecCallSession extends InboundCallSession {
         headers: {
           'Content-Type': 'application/sdp',
           'X-Trace-ID': this.req.locals.traceId,
-          'X-Call-Sid': this.req.locals.callSid
+          'X-Call-Sid': this.req.locals.callSid,
+          ...(this.applicationSid && {'X-Application-Sid': this.applicationSid})
         },
         localSdp: combinedSdp
       });
diff --git a/lib/utils/place-outdial.js b/lib/utils/place-outdial.js
index 3b7a6fc3..f08ed760 100644
--- a/lib/utils/place-outdial.js
+++ b/lib/utils/place-outdial.js
@@ -67,7 +67,8 @@ class SingleDialer extends Emitter {
       ...opts.headers,
       ...(this.target.headers || {}),
       'X-Jambonz-Routing': this.target.type,
-      'X-Call-Sid': this.callSid
+      'X-Call-Sid': this.callSid,
+      ...(this.applicationSid && {'X-Application-Sid': this.applicationSid})
     };
     if (srf.locals.fsUUID) {
       opts.headers = {