diff --git a/app/main/views/conversation.py b/app/main/views/conversation.py
index 783e244fd..ffbda324f 100644
--- a/app/main/views/conversation.py
+++ b/app/main/views/conversation.py
@@ -33,23 +33,23 @@ def get_user_number(service_id, notification_id):
 
 
 def get_sms_thread(service_id, user_number):
-    return [
-        {
-            'inbound': ('notify_number' in notification),
+
+    for notification in sorted((
+        notification_api_client.get_notifications_for_service(service_id, to=user_number)['notifications'] +
+        service_api_client.get_inbound_sms(service_id, user_number=user_number)
+    ), key=lambda notification: notification['created_at']):
+
+        is_inbound = ('notify_number' in notification)
+
+        yield {
+            'inbound': is_inbound,
             'content': SMSPreviewTemplate(
                 {
                     'content': notification.get('content') or notification['template']['content']
-                }
+                },
+                downgrade_non_gsm_characters=(not is_inbound)
             ),
             'created_at': notification['created_at'],
             'status': notification.get('status'),
             'id': notification['id'],
         }
-        for notification in sorted(
-            (
-                notification_api_client.get_notifications_for_service(service_id, to=user_number)['notifications'] +
-                service_api_client.get_inbound_sms(service_id, user_number=user_number)
-            ),
-            key=lambda notification: notification['created_at'],
-        )
-    ]
diff --git a/requirements.txt b/requirements.txt
index 03158b9fd..ff93059fc 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -28,4 +28,4 @@ notifications-python-client>=3.1,<3.2
 awscli>=1.11,<1.12
 awscli-cwlogs>=1.4,<1.5
 
-git+https://github.com/alphagov/notifications-utils.git@17.2.0#egg=notifications-utils==17.2.0
+git+https://github.com/alphagov/notifications-utils.git@17.3.0#egg=notifications-utils==17.3.0
diff --git a/tests/app/main/views/test_conversation.py b/tests/app/main/views/test_conversation.py
index a9ad71369..26f845b19 100644
--- a/tests/app/main/views/test_conversation.py
+++ b/tests/app/main/views/test_conversation.py
@@ -76,8 +76,6 @@ def test_view_conversation(
     expected,
 ):
 
-    print(index)
-
     response = logged_in_client.get(url_for(
         'main.conversation',
         service_id=SERVICE_ONE_ID,
@@ -89,9 +87,8 @@ def test_view_conversation(
     messages = page.select('.sms-message-wrapper')
     statuses = page.select('.sms-message-status')
 
-    for elements in (messages, statuses):
-        assert len(elements) == 13
-
+    assert len(messages) == 13
+    assert len(statuses) == 13
     assert (
         normalize_spaces(messages[index].text),
         normalize_spaces(statuses[index].text),