diff --git a/app/main/views/send.py b/app/main/views/send.py
index 560c5cb3a..6ef2afc77 100644
--- a/app/main/views/send.py
+++ b/app/main/views/send.py
@@ -1,4 +1,3 @@
-import itertools
 import time
 import uuid
 from string import ascii_uppercase
@@ -517,19 +516,27 @@ def _check_messages(service_id, template_id, upload_id, preview_row):
         current_service,
         show_recipient=False,
     )
+
+    allow_list = []
+    if current_service.trial_mode:
+        # Adding the simulated numbers to allow list
+        # so they can be sent in trial mode
+        for user in Users(service_id):
+            allow_list.extend([user.name, user.mobile_number, user.email_address])
+        # Failed sms number
+        allow_list.extend(["simulated user (fail)", "+14254147167", "simulated@simulated.gov"])
+        # Success sms number
+        allow_list.extend(
+            ["simulated user (success)", "+14254147755", "simulatedtwo@simulated.gov"]
+        )
+    else:
+        allow_list = None
     recipients = RecipientCSV(
         contents,
         template=template or simplifed_template,
         max_initial_rows_shown=50,
         max_errors_shown=50,
-        guestlist=(
-            itertools.chain.from_iterable(
-                [user.name, user.mobile_number, user.email_address]
-                for user in Users(service_id)
-            )
-            if current_service.trial_mode
-            else None
-        ),
+        guestlist=allow_list,
         remaining_messages=remaining_messages,
         allow_international_sms=current_service.has_permission("international_sms"),
     )