diff --git a/app/dao/notifications_dao.py b/app/dao/notifications_dao.py
index feaad7fea..f531a15c6 100644
--- a/app/dao/notifications_dao.py
+++ b/app/dao/notifications_dao.py
@@ -1,4 +1,5 @@
 import functools
+import string
 from datetime import (
     datetime,
     timedelta,
@@ -425,7 +426,10 @@ def dao_update_notifications_by_reference(references, update_dict):
 
 
 @statsd(namespace="dao")
-def dao_get_notifications_by_to_field(service_id, search_term, notification_type, statuses=None):
+def dao_get_notifications_by_to_field(service_id, search_term, notification_type=None, statuses=None):
+
+    if notification_type is None:
+        notification_type = guess_notification_type(search_term)
 
     if notification_type == SMS_TYPE:
         normalised = try_validate_and_format_phone_number(search_term)
@@ -440,6 +444,7 @@ def dao_get_notifications_by_to_field(service_id, search_term, notification_type
             normalised = validate_and_format_email_address(search_term)
         except InvalidEmailError:
             normalised = search_term.lower()
+
     else:
         raise InvalidRequest("Only email and SMS can use search by recipient", 400)
 
@@ -597,3 +602,10 @@ def notifications_not_yet_sent(should_be_sending_after_seconds, notification_typ
         Notification.status == NOTIFICATION_CREATED
     ).all()
     return notifications
+
+
+def guess_notification_type(search_term):
+    if set(search_term) & set(string.ascii_letters + '@'):
+        return EMAIL_TYPE
+    else:
+        return SMS_TYPE
diff --git a/tests/app/dao/notification_dao/test_notification_dao.py b/tests/app/dao/notification_dao/test_notification_dao.py
index 4c9e3bca2..775598015 100644
--- a/tests/app/dao/notification_dao/test_notification_dao.py
+++ b/tests/app/dao/notification_dao/test_notification_dao.py
@@ -1553,20 +1553,34 @@ def test_dao_get_notifications_by_to_field_search_ignores_spaces(sample_template
     assert notification3.id in notification_ids
 
 
-def test_dao_get_notifications_by_to_field_only_searches_for_notification_type(
-    notify_db_session
+@pytest.mark.parametrize('phone_search', (
+    '077', '7-7', '+44(0)7711 111111'
+))
+@pytest.mark.parametrize('email_search', (
+    'example', 'eXaMpLe',
+))
+def test_dao_get_notifications_by_to_field_only_searches_one_notification_type(
+    notify_db_session,
+    phone_search,
+    email_search,
 ):
     service = create_service()
     sms_template = create_template(service=service)
     email_template = create_template(service=service, template_type='email')
-    sms = create_notification(template=sms_template, to_field='0771111111', normalised_to='0771111111')
+    sms = create_notification(template=sms_template, to_field='07711111111', normalised_to='447711111111')
     email = create_notification(
         template=email_template, to_field='077@example.com', normalised_to='077@example.com'
     )
-    results = dao_get_notifications_by_to_field(service.id, "077", notification_type='sms')
+    results = dao_get_notifications_by_to_field(service.id, phone_search, notification_type='sms')
     assert len(results) == 1
     assert results[0].id == sms.id
-    results = dao_get_notifications_by_to_field(service.id, "077", notification_type='email')
+    results = dao_get_notifications_by_to_field(service.id, phone_search)  # should assume SMS
+    assert len(results) == 1
+    assert results[0].id == sms.id
+    results = dao_get_notifications_by_to_field(service.id, '077', notification_type='email')
+    assert len(results) == 1
+    assert results[0].id == email.id
+    results = dao_get_notifications_by_to_field(service.id, email_search)  # should assume email
     assert len(results) == 1
     assert results[0].id == email.id