bugfix: to move call leg to a different FS using the special REFER, we now must include X-Account-Sid header

lib/session/call-session.js

@@ -1466,7 +1466,8 @@ class CallSession extends Emitter {
       headers: {
         'Refer-To': referTo,
         'Referred-By': `sip:${this.srf.locals.localSipAddress}`,
-        'X-Retain-Call-Sid': this.callSid
+        'X-Retain-Call-Sid': this.callSid,
+        'X-Account-Sid': this.accountSid
       }
     });
     if ([200, 202].includes(res.status)) {