This PR adds the ability to select a text message sender if more than one exist for the service.

app/utils.py

@@ -272,6 +272,7 @@ def get_template(
     page_count=1,
     redact_missing_personalisation=False,
     email_reply_to=None,
+    sms_sender=None
 ):
     if 'email' == template['template_type']:
         return EmailPreviewTemplate(
@@ -287,7 +288,7 @@ def get_template(
         return SMSPreviewTemplate(
             template,
             prefix=service['name'],
-            sender=(service['sms_sender'] not in {'GOVUK', None}),
+            sender=sms_sender if sms_sender else (service['sms_sender'] not in {'GOVUK', None}),
             show_recipient=show_recipient,
             redact_missing_personalisation=redact_missing_personalisation,
         )