diff --git a/app/main/views/service_settings.py b/app/main/views/service_settings.py
index 56fe13772..97cf75fad 100644
--- a/app/main/views/service_settings.py
+++ b/app/main/views/service_settings.py
@@ -270,7 +270,7 @@ def service_set_sms_sender(service_id):
     form = ServiceSmsSender()
     if form.validate_on_submit():
         set_inbound_sms = request.args.get('set_inbound_sms', False)
-        if set_inbound_sms:
+        if set_inbound_sms == 'True':
             permissions = current_service['permissions']
             if 'inbound_sms' in permissions:
                 permissions.remove('inbound_sms')
diff --git a/tests/app/main/views/test_service_settings.py b/tests/app/main/views/test_service_settings.py
index 73de6916c..4d9ba1814 100644
--- a/tests/app/main/views/test_service_settings.py
+++ b/tests/app/main/views/test_service_settings.py
@@ -681,6 +681,30 @@ def test_turn_inbound_sms_off(
     assert app.current_service['permissions'] == []
 
 
+def test_set_text_message_sender_and_not_inbound_sms(
+    logged_in_client,
+    service_one,
+    mock_get_letter_organisations,
+    mocker,
+):
+    service_one['permissions'] = []
+    update_service_mock = mocker.patch('app.service_api_client.update_service',
+                                       return_value=service_one)
+
+    data = {"sms_sender": "elevenchars"}
+    response = logged_in_client.post(url_for('main.service_set_sms_sender', service_id=service_one['id'],
+                                             set_inbound_sms=False),
+                                     data=data,
+                                     follow_redirects=True)
+    assert response.status_code == 200
+
+    update_service_mock.assert_called_with(
+        service_one['id'],
+        sms_sender="elevenchars"
+    )
+    assert app.current_service['permissions'] == []
+
+
 @pytest.mark.parametrize('content, expected_error', [
     ("", "Can’t be empty"),
     ("twelvecharss", "Enter 11 characters or fewer"),