treat 40604 and GOVUK as not having a sender ID

in prep for removing the 40604-as-default, first we need to make sure
that if you either have GOVUK or None as your sms sender, then we send
GOVUK through to the provider

app/config.py

@@ -287,7 +287,7 @@ class Live(Config):
     NOTIFY_ENVIRONMENT = 'live'
     CSV_UPLOAD_BUCKET_NAME = 'live-notifications-csv-upload'
     STATSD_ENABLED = True
-    FROM_NUMBER = '40604'
+    FROM_NUMBER = 'GOVUK'
     FUNCTIONAL_TEST_PROVIDER_SERVICE_ID = '6c1d81bb-dae2-4ee9-80b0-89a4aae9f649'
     FUNCTIONAL_TEST_PROVIDER_SMS_TEMPLATE_ID = 'ba9e1789-a804-40b8-871f-cc60d4c1286f'
     PERFORMANCE_PLATFORM_ENABLED = True

app/delivery/send_to_providers.py

@@ -23,6 +23,7 @@ from app.celery.statistics_tasks import record_initial_job_statistics, create_in
 
 def send_sms_to_provider(notification):
     service = notification.service
+
     if not service.active:
         technical_failure(notification=notification)
         return
@@ -37,7 +38,7 @@ def send_sms_to_provider(notification):
             template_model.__dict__,
             values=notification.personalisation,
             prefix=service.name,
-            sender=service.sms_sender
+            sender=service.sms_sender not in {None, current_app.config['FROM_NUMBER']}
         )
 
         if service.research_mode or notification.key_type == KEY_TYPE_TEST:
@@ -50,7 +51,7 @@ def send_sms_to_provider(notification):
                     to=validate_and_format_phone_number(notification.to, international=notification.international),
                     content=str(template),
                     reference=str(notification.id),
-                    sender=service.sms_sender
+                    sender=service.sms_sender or current_app.config['FROM_NUMBER']
                 )
             except Exception as e:
                 dao_toggle_sms_provider(provider.name)