support SIP Privacy (#970)

lib/tasks/dial.js

@@ -500,8 +500,10 @@ class TaskDial extends Task {
       'X-Account-Sid': cs.accountSid,
       ...(req && req.has('X-CID') && {'X-CID': req.get('X-CID')}),
       ...(direction === 'outbound' && callInfo.sbcCallid && {'X-CID': callInfo.sbcCallid}),
-      ...(req && req.has('P-Asserted-Identity') && !JAMBONZ_DISABLE_DIAL_PAI_HEADER &&
-        {'P-Asserted-Identity': req.get('P-Asserted-Identity')}),
+      ...(!JAMBONZ_DISABLE_DIAL_PAI_HEADER && req && {
+        ...(req.has('P-Asserted-Identity') && {'P-Asserted-Identity': req.get('P-Asserted-Identity')}),
+        ...(req.has('Privacy') && {'Privacy': req.get('Privacy')}),
+      }),
       ...(req && req.has('X-Voip-Carrier-Sid') && {'X-Voip-Carrier-Sid': req.get('X-Voip-Carrier-Sid')}),
       // Put headers at the end to make sure opt.headers override all default behavior.
       ...this.headers