diff --git a/lib/tasks/dial.js b/lib/tasks/dial.js
index d14397fe..d9ca0963 100644
--- a/lib/tasks/dial.js
+++ b/lib/tasks/dial.js
@@ -340,15 +340,17 @@ class TaskDial extends Task {
 
         const to = parseUri(req.getParsedHeader('Refer-To').uri);
         const by = parseUri(req.getParsedHeader('Referred-By').uri);
+        const referredBy = req.get('Referred-By');
+        const userAgent = req.get('User-Agent');
         this.logger.info({to}, 'refer to parsed');
         const json = await cs.requestor.request('verb:hook', this.referHook, {
           ...(callInfo.toJSON()),
           refer_details: {
             sip_refer_to: req.get('Refer-To'),
-            sip_referred_by: req.get('Referred-By'),
-            sip_user_agent: req.get('User-Agent'),
             refer_to_user: to.scheme === 'tel' ? to.number : to.user,
-            referred_by_user: by.scheme === 'tel' ? by.number : by.user,
+            ...(referredBy && {sip_referred_by: referredBy}),
+            ...(userAgent && {sip_user_agent: userAgent}),
+            ...(by && {referred_by_user: by.scheme === 'tel' ? by.number : by.user}),
             referring_call_sid,
             referred_call_sid
           }
@@ -379,6 +381,7 @@ class TaskDial extends Task {
         res.send(202);
         this.logger.info('DialTask:handleRefer - sent 202 Accepted');
       } catch (err) {
+        this.logger.info({err}, 'DialTask:handleRefer - error processing incoming REFER');
         res.send(err.statusCode || 501);
       }
     }