diff --git a/vumi_twilio_api/tests/test_twilio_api.py b/vumi_twilio_api/tests/test_twilio_api.py
index 6c3aded..5c5c5d1 100644
--- a/vumi_twilio_api/tests/test_twilio_api.py
+++ b/vumi_twilio_api/tests/test_twilio_api.py
@@ -408,7 +408,8 @@ def test_make_call_parsing_play_verb(self):
         [msg] = yield self.app_helper.wait_for_dispatched_outbound(1)
         yield self.app_helper.dispatch_event(self.app_helper.make_ack(msg))
         [_, reply] = yield self.app_helper.wait_for_dispatched_outbound(1)
-        self.assertEqual(reply['helper_metadata']['voice']['url'], 'test_url')
+        self.assertEqual(
+            reply['helper_metadata']['voice']['speech_url'], 'test_url')
         self.assertEqual(reply['from_addr'], '+12345')
         self.assertEqual(reply['to_addr'], '+54321')
 
@@ -472,7 +473,8 @@ def test_receive_call_parsing_play_verb(self):
         yield self.app_helper.dispatch_inbound(msg)
         [reply] = yield self.app_helper.wait_for_dispatched_outbound(1)
 
-        self.assertEqual(reply['helper_metadata']['voice']['url'], 'test_url')
+        self.assertEqual(
+            reply['helper_metadata']['voice']['speech_url'], 'test_url')
         self.assertEqual(reply['in_reply_to'], msg['message_id'])
 
     @inlineCallbacks
diff --git a/vumi_twilio_api/twilio_api.py b/vumi_twilio_api/twilio_api.py
index ff55441..d84a49b 100644
--- a/vumi_twilio_api/twilio_api.py
+++ b/vumi_twilio_api/twilio_api.py
@@ -162,7 +162,7 @@ def _handle_connected_call(
     def _send_message(self, url, session, session_event=None):
         helper_metadata = {}
         if url:
-            helper_metadata['voice'] = {'url': url}
+            helper_metadata['voice'] = {'speech_url': url}
 
         return self.send_to(
             session['To'], '',
@@ -220,7 +220,7 @@ def new_session(self, message):
             elif verb.name == "Play":
                 yield self.reply_to(message, '', helper_metadata={
                     'voice': {
-                        'url': verb.nouns[0],
+                        'speech_url': verb.nouns[0],
                         }
                     })
             elif verb.name == "Hangup":