diff --git a/public/message/output/sms/tests/message_output_sms_test.php b/public/message/output/sms/tests/message_output_sms_test.php
index 454e25da0c3..7c7cea567bf 100644
--- a/public/message/output/sms/tests/message_output_sms_test.php
+++ b/public/message/output/sms/tests/message_output_sms_test.php
@@ -100,6 +100,7 @@ final class message_output_sms_test extends \advanced_testcase {
         $this->assertCount(1, $adhoctask);
 
         // Now lets run the task and check if SMS is sent.
+        $this->expectOutputRegex('/SMS send status: gateway_sent/');
         $this->run_all_adhoc_tasks();
 
         $message = $manager->get_message(['id' => $message->id]);
diff --git a/public/sms/classes/task/send_sms_task.php b/public/sms/classes/task/send_sms_task.php
index 952eaf9ce2f..3c84732a325 100644
--- a/public/sms/classes/task/send_sms_task.php
+++ b/public/sms/classes/task/send_sms_task.php
@@ -18,6 +18,7 @@ namespace core_sms\task;
 
 use core\task\adhoc_task;
 use core_sms\message;
+use core_sms\message_status;
 
 /**
  * Ad-hoc task to send an SMS.
@@ -39,11 +40,23 @@ class send_sms_task extends adhoc_task {
         $message = $manager->get_message(
             filter: ['id' => $smsdata->messageid],
         );
-        $manager->send_message(
+        $message = $manager->send_message(
             message: $message,
             async: false,
         );
+        $status = $message?->status;
+        $retryfailures = [
+            message_status::GATEWAY_FAILED,
+            message_status::GATEWAY_NOT_AVAILABLE,
+        ];
 
+        if (in_array($status, $retryfailures)) {
+            // Only retry if the failure encountered will possibly resolve in subsequent attempts.
+            mtrace("SMS failed status: {$status?->value} - task will retry");
+            throw new \moodle_exception('SMS Gateway encountered a failure');
+        } else {
+            mtrace("SMS send status: " . ($status?->value ?? message_status::UNKNOWN->value));
+        }
     }
 
     /**
diff --git a/public/sms/gateway/aws/classes/local/service/aws_sns.php b/public/sms/gateway/aws/classes/local/service/aws_sns.php
index eed04e14345..4371b71d5ab 100644
--- a/public/sms/gateway/aws/classes/local/service/aws_sns.php
+++ b/public/sms/gateway/aws/classes/local/service/aws_sns.php
@@ -59,18 +59,19 @@ class aws_sns implements aws_sms_service_provider {
         $senderid = substr($senderid, 0, 11);
 
         try {
-            // These messages need to be transactional.
-            $client->SetSMSAttributes([
-                'attributes' => [
-                    'DefaultSMSType' => 'Transactional',
-                    'DefaultSenderID' => $senderid,
-                ],
-            ]);
-
-            // Actually send the message.
             $client->publish([
                 'Message' => $messagecontent,
                 'PhoneNumber' => $phonenumber,
+                'MessageAttributes' => [
+                    'AWS.SNS.SMS.SenderID' => [
+                        'DataType' => 'String',
+                        'StringValue' => $senderid,
+                    ],
+                    'AWS.SNS.SMS.SMSType' => [
+                        'DataType' => 'String',
+                        'StringValue' => 'Transactional',
+                    ],
+                ],
             ]);
             return \core_sms\message_status::GATEWAY_SENT;
         } catch (\Aws\Exception\AwsException $e) {
diff --git a/public/sms/tests/manager_test.php b/public/sms/tests/manager_test.php
index 320dc9553c5..8f21dff8610 100644
--- a/public/sms/tests/manager_test.php
+++ b/public/sms/tests/manager_test.php
@@ -465,6 +465,7 @@ final class manager_test extends \advanced_testcase {
         $this->assertCount(1, $adhoctask);
 
         // Now lets run the task and check if SMS is sent.
+        $this->expectOutputRegex('/SMS send status: gateway_sent/');
         $this->run_all_adhoc_tasks();
 
         $message = $manager->get_message(['id' => $message->id]);
@@ -551,4 +552,41 @@ final class manager_test extends \advanced_testcase {
         $this->assertCount(1, $messages);
         array_walk($messages, fn ($message) => $this->assertInstanceOf(message::class, $message));
     }
+
+    /**
+     * Test async message is resent when gateway is not available.
+     */
+    public function test_resend_when_gateway_not_available(): void {
+        $this->resetAfterTest();
+
+        $manager = \core\di::get(\core_sms\manager::class);
+
+        $message = $manager->send(
+            recipientnumber: '+447123456789',
+            content: 'Hello, world!',
+            component: 'core',
+            messagetype: 'test',
+            recipientuserid: null,
+            async: true,
+        );
+
+        $messagedbrecords = $manager->get_messages();
+        $messages = iterator_to_array($messagedbrecords);
+        $this->assertCount(1, $messages);
+
+        $adhoctask = \core\task\manager::get_adhoc_tasks(send_sms_task::class);
+        $this->assertCount(1, $adhoctask);
+
+        try {
+            $this->expectOutputRegex('/SMS failed status: gateway_not_available - task will retry/');
+            $this->run_all_adhoc_tasks();
+            $this->fail('Exception expected');
+        } catch (\moodle_exception $e) {
+            $message = $manager->get_message(['id' => $message->id]);
+            $this->assertEquals(message_status::GATEWAY_NOT_AVAILABLE, $message->status);
+
+            $adhoctask = \core\task\manager::get_adhoc_tasks(send_sms_task::class);
+            $this->assertCount(1, $adhoctask);
+        }
+    }
 }