diff --git a/sylk/applications/webrtcgateway/push.py b/sylk/applications/webrtcgateway/push.py
index b56b338..937ff76 100644
--- a/sylk/applications/webrtcgateway/push.py
+++ b/sylk/applications/webrtcgateway/push.py
@@ -1,81 +1,81 @@
 
 import json
 
 from sipsimple.util import ISOTimestamp
 from twisted.internet import defer, reactor
 from twisted.web.client import Agent
 from twisted.web.iweb import IBodyProducer
 from twisted.web.http_headers import Headers
 from zope.interface import implementer
 
 from sylk.applications.webrtcgateway.configuration import GeneralConfig
 from sylk.applications.webrtcgateway.logger import log
 
 
 __all__ = 'incoming_session', 'missed_session'
 
 
 agent = Agent(reactor)
 headers = Headers({'User-Agent': ['SylkServer'],
                    'Content-Type': ['application/json'],
                    'Authorization': ['key=%s' % GeneralConfig.firebase_server_key]})
 FIREBASE_API_URL = 'https://fcm.googleapis.com/fcm/send'
 
 
 @implementer(IBodyProducer)
 class StringProducer(object):
     def __init__(self, data):
         self.body = data
         self.length = len(data)
 
     def startProducing(self, consumer):
         consumer.write(self.body)
         return defer.succeed(None)
 
     def pauseProducing(self):
         pass
 
     def stopProducing(self):
         pass
 
 
 def incoming_session(originator, destination, tokens):
     for token in tokens:
         data = dict(to=token, notification={}, data={'sylkrtc': {}}, content_available=True)
         data['notification']['body'] = 'Incoming call from %s' % originator
         data['notification']['sound'] = 'Blow'
         data['priority'] = 'high'
         data['time_to_live'] = 60    # don't deliver if phone is out for over a minute
         data['data']['sylkrtc']['event'] = 'incoming_session'
         data['data']['sylkrtc']['originator'] = originator
         data['data']['sylkrtc']['destination'] = destination
-        data['data']['sylkrtc']['timestamp'] = str(ISOTimestamp.now())
+        data['data']['sylkrtc']['timestamp'] = str(ISOTimestamp.utcnow())
         _send_push_notification(json.dumps(data))
 
 
 def missed_session(originator, destination, tokens):
     for token in tokens:
         data = dict(to=token, notification={}, data={'sylkrtc': {}}, content_available=True)
         data['notification']['body'] = 'Missed call from %s' % originator
         data['notification']['sound'] = 'Blow'
         data['priority'] = 'high'
         # No TTL, default is 4 weeks
         data['data']['sylkrtc']['event'] = 'missed_session'
         data['data']['sylkrtc']['originator'] = originator
         data['data']['sylkrtc']['destination'] = destination
-        data['data']['sylkrtc']['timestamp'] = str(ISOTimestamp.now())
+        data['data']['sylkrtc']['timestamp'] = str(ISOTimestamp.utcnow())
         _send_push_notification(json.dumps(data))
 
 
 @defer.inlineCallbacks
 def _send_push_notification(payload):
     if GeneralConfig.firebase_server_key:
         try:
             r = yield agent.request('POST', FIREBASE_API_URL, headers, StringProducer(payload))
         except Exception as e:
             log.info('Error sending Firebase message: %s', e)
         else:
             if r.code != 200:
                 log.warn('Error sending Firebase message: %s' % r.phrase)
     else:
         log.warn('Cannot send push notification: no Firebase server key configured')