diff --git a/src/djangooidc/backends.py b/src/djangooidc/backends.py
index 69b34d775..6556d8d7a 100644
--- a/src/djangooidc/backends.py
+++ b/src/djangooidc/backends.py
@@ -8,6 +8,8 @@ from django.contrib.auth import get_user_model
 from django.contrib.auth.backends import ModelBackend
 from django.utils import timezone
 
+from registrar.models.contact import Contact
+
 logger = logging.getLogger(__name__)
 
 
@@ -80,6 +82,14 @@ class OpenIdConnectBackend(ModelBackend):
             - 'first_name' and 'last_name' will be updated if the provided value is not empty.
         """
 
+        contacts = Contact.objects.filter(user=user)
+
+        if len(contacts) == 0:  # no matching contact
+            logger.warning("Could not find a contact when one should've existed.")
+
+        if len(contacts) > 1:  # multiple matches
+            logger.warning("There are multiple Contacts with the same email address.")
+
         # Iterate over fields to update
         for key, value in kwargs.items():
             # Check if the field is not 'first_name', 'last_name', or 'phone',
@@ -87,7 +97,7 @@ class OpenIdConnectBackend(ModelBackend):
             # or if it's 'first_name' or 'last_name' and the provided value is not empty
             if (
                 key not in ["first_name", "last_name", "phone"]
-                or (key == "phone" and (user.phone is None or user.phone == ""))
+                or (key == "phone" and not contacts[0].phone)
                 or (key in ["first_name", "last_name"] and value)
             ):
                 # Update the corresponding attribute of the user object
diff --git a/src/registrar/models/contact.py b/src/registrar/models/contact.py
index 9deb22641..185b84ded 100644
--- a/src/registrar/models/contact.py
+++ b/src/registrar/models/contact.py
@@ -102,9 +102,10 @@ class Contact(TimeStampedModel):
         super().save(*args, **kwargs)
 
         # Update the related User object's first_name and last_name
-        if self.user and (not self.user.first_name or not self.user.last_name):
+        if self.user and (not self.user.first_name or not self.user.last_name or not self.user.phone):
             self.user.first_name = self.first_name
             self.user.last_name = self.last_name
+            self.user.phone = self.phone
             self.user.save()
 
     def __str__(self):
diff --git a/src/registrar/tests/common.py b/src/registrar/tests/common.py
index 6dd88c1c1..b895e2916 100644
--- a/src/registrar/tests/common.py
+++ b/src/registrar/tests/common.py
@@ -834,7 +834,7 @@ def completed_domain_request(
     )
     if not investigator:
         investigator, _ = User.objects.get_or_create(
-            username="incrediblyfakeinvestigator",
+            username="incrediblyfakeinvestigator" + str(uuid.uuid4())[:8],
             first_name="Joe",
             last_name="Bob",
             is_staff=True,
diff --git a/src/registrar/tests/test_models.py b/src/registrar/tests/test_models.py
index ca77d1ddf..1558ab310 100644
--- a/src/registrar/tests/test_models.py
+++ b/src/registrar/tests/test_models.py
@@ -1152,12 +1152,18 @@ class TestContact(TestCase):
     def setUp(self):
         self.email_for_invalid = "intern@igorville.gov"
         self.invalid_user, _ = User.objects.get_or_create(
-            username=self.email_for_invalid, email=self.email_for_invalid, first_name="", last_name=""
+            username=self.email_for_invalid,
+            email=self.email_for_invalid,
+            first_name="",
+            last_name="",
+            phone="",
         )
         self.invalid_contact, _ = Contact.objects.get_or_create(user=self.invalid_user)
 
         self.email = "mayor@igorville.gov"
-        self.user, _ = User.objects.get_or_create(email=self.email, first_name="Jeff", last_name="Lebowski")
+        self.user, _ = User.objects.get_or_create(
+            email=self.email, first_name="Jeff", last_name="Lebowski", phone="123456789"
+        )
         self.contact, _ = Contact.objects.get_or_create(user=self.user)
 
         self.contact_as_ao, _ = Contact.objects.get_or_create(email="newguy@igorville.gov")
@@ -1169,19 +1175,22 @@ class TestContact(TestCase):
         Contact.objects.all().delete()
         User.objects.all().delete()
 
-    def test_saving_contact_updates_user_first_last_names(self):
+    def test_saving_contact_updates_user_first_last_names_and_phone(self):
         """When a contact is updated, we propagate the changes to the linked user if it exists."""
 
         # User and Contact are created and linked as expected.
         # An empty User object should create an empty contact.
         self.assertEqual(self.invalid_contact.first_name, "")
         self.assertEqual(self.invalid_contact.last_name, "")
+        self.assertEqual(self.invalid_contact.phone, "")
         self.assertEqual(self.invalid_user.first_name, "")
         self.assertEqual(self.invalid_user.last_name, "")
+        self.assertEqual(self.invalid_user.phone, "")
 
         # Manually update the contact - mimicking production (pre-existing data)
         self.invalid_contact.first_name = "Joey"
         self.invalid_contact.last_name = "Baloney"
+        self.invalid_contact.phone = "123456789"
         self.invalid_contact.save()
 
         # Refresh the user object to reflect the changes made in the database
@@ -1190,20 +1199,25 @@ class TestContact(TestCase):
         # Updating the contact's first and last names propagate to the user
         self.assertEqual(self.invalid_contact.first_name, "Joey")
         self.assertEqual(self.invalid_contact.last_name, "Baloney")
+        self.assertEqual(self.invalid_contact.phone, "123456789")
         self.assertEqual(self.invalid_user.first_name, "Joey")
         self.assertEqual(self.invalid_user.last_name, "Baloney")
+        self.assertEqual(self.invalid_user.phone, "123456789")
 
-    def test_saving_contact_does_not_update_user_first_last_names(self):
+    def test_saving_contact_does_not_update_user_first_last_names_and_phone(self):
         """When a contact is updated, we avoid propagating the changes to the linked user if it already has a value"""
 
         # User and Contact are created and linked as expected
         self.assertEqual(self.contact.first_name, "Jeff")
         self.assertEqual(self.contact.last_name, "Lebowski")
+        self.assertEqual(self.contact.phone, "123456789")
         self.assertEqual(self.user.first_name, "Jeff")
         self.assertEqual(self.user.last_name, "Lebowski")
+        self.assertEqual(self.user.phone, "123456789")
 
         self.contact.first_name = "Joey"
         self.contact.last_name = "Baloney"
+        self.contact.phone = "987654321"
         self.contact.save()
 
         # Refresh the user object to reflect the changes made in the database
@@ -1212,8 +1226,10 @@ class TestContact(TestCase):
         # Updating the contact's first and last names propagate to the user
         self.assertEqual(self.contact.first_name, "Joey")
         self.assertEqual(self.contact.last_name, "Baloney")
+        self.assertEqual(self.contact.phone, "987654321")
         self.assertEqual(self.user.first_name, "Jeff")
         self.assertEqual(self.user.last_name, "Lebowski")
+        self.assertEqual(self.user.phone, "123456789")
 
     def test_saving_contact_does_not_update_user_email(self):
         """When a contact's email is updated, the change is not propagated to the user."""