diff --git a/xos/synchronizer/steps/sync_att_workflow_driver_service_instance.py b/xos/synchronizer/steps/sync_att_workflow_driver_service_instance.py
new file mode 100644
index 0000000..d2fdeeb
--- /dev/null
+++ b/xos/synchronizer/steps/sync_att_workflow_driver_service_instance.py
@@ -0,0 +1,63 @@
+# Copyright 2017-present Open Networking Foundation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import json
+from synchronizers.new_base.syncstep import SyncStep, model_accessor
+from synchronizers.new_base.modelaccessor import AttWorkflowDriverServiceInstance, AttWorkflowDriverWhiteListEntry
+
+from xosconfig import Config
+from multistructlog import create_logger
+
+log = create_logger(Config().get('logging'))
+
+class SyncAttWorkflowDriverServiceInstance(SyncStep):
+    provides = [AttWorkflowDriverServiceInstance]
+    observes = AttWorkflowDriverServiceInstance
+
+    def validate_in_external_oss(self, si):
+        # This is where you may want to call your OSS Database to verify if this ONU can be activated
+        oss_service = si.owner.leaf_model
+
+        # See if there is a matching entry in the whitelist.
+
+        matching_entries = AttWorkflowDriverWhiteListEntry.objects.filter(owner_id=oss_service.id,
+                                                                  serial_number=si.serial_number)
+
+        return len(matching_entries)>0
+
+    def get_suscriber_c_tag(self, serial_number):
+        # If it's up to your OSS to generate c_tags, fetch them here
+        # otherwise XOS will generate one for your subscriber
+        return None
+
+    def sync_record(self, o):
+        log.info("synching AttWorkflowDriverServiceInstance", object=str(o), **o.tologdict())
+
+        if not self.validate_in_external_oss(o):
+            log.error("ONU with serial number %s is not valid in the OSS Database" % o.serial_number)
+            o.valid = "invalid"
+        else:
+            if self.get_suscriber_c_tag(o.serial_number):
+                self.c_tag = self.get_suscriber_c_tag(o.serial_number)
+
+            o.valid = "valid"
+
+        # Set no_sync=True to prevent the syncstep from running again, and set alway_update_timestamp=True to cause
+        # the model_policy to run again.
+        # TODO(smbaker): Revisit this after fixing this issue in the core.
+        o.no_sync = True
+        o.save(update_fields=["valid", "no_sync", "updated"], always_update_timestamp=True)
+
+    def delete_record(self, o):
+        pass
diff --git a/xos/synchronizer/steps/test_sync_att_workflow_driver_service_instance.py b/xos/synchronizer/steps/test_sync_att_workflow_driver_service_instance.py
new file mode 100644
index 0000000..db168f7
--- /dev/null
+++ b/xos/synchronizer/steps/test_sync_att_workflow_driver_service_instance.py
@@ -0,0 +1,114 @@
+# Copyright 2017-present Open Networking Foundation
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import unittest
+
+import functools
+from mock import patch, call, Mock, PropertyMock
+import requests_mock
+import multistructlog
+from multistructlog import create_logger
+
+import os, sys
+
+# Hack to load synchronizer framework
+test_path=os.path.abspath(os.path.dirname(os.path.realpath(__file__)))
+xos_dir=os.path.join(test_path, "../../..")
+if not os.path.exists(os.path.join(test_path, "new_base")):
+    xos_dir=os.path.join(test_path, "../../../../../../orchestration/xos/xos")
+    services_dir = os.path.join(xos_dir, "../../xos_services")
+sys.path.append(xos_dir)
+sys.path.append(os.path.join(xos_dir, 'synchronizers', 'new_base'))
+# END Hack to load synchronizer framework
+
+# generate model from xproto
+def get_models_fn(service_name, xproto_name):
+    name = os.path.join(service_name, "xos", xproto_name)
+    if os.path.exists(os.path.join(services_dir, name)):
+        return name
+    else:
+        name = os.path.join(service_name, "xos", "synchronizer", "models", xproto_name)
+        if os.path.exists(os.path.join(services_dir, name)):
+            return name
+    raise Exception("Unable to find service=%s xproto=%s" % (service_name, xproto_name))
+# END generate model from xproto
+
+class TestSyncAttWorkflowDriverServiceInstance(unittest.TestCase):
+
+    def setUp(self):
+
+        self.sys_path_save = sys.path
+        sys.path.append(xos_dir)
+        sys.path.append(os.path.join(xos_dir, 'synchronizers', 'new_base'))
+
+        # Setting up the config module
+        from xosconfig import Config
+        config = os.path.join(test_path, "../test_config.yaml")
+        Config.clear()
+        Config.init(config, "synchronizer-config-schema.yaml")
+        # END Setting up the config module
+
+        from synchronizers.new_base.mock_modelaccessor_build import build_mock_modelaccessor
+        build_mock_modelaccessor(xos_dir, services_dir, [
+            get_models_fn("att-workflow-driver", "att-workflow-driver.xproto"),
+            get_models_fn("olt-service", "volt.xproto"),
+            get_models_fn("../profiles/rcord", "rcord.xproto")
+        ])
+        import synchronizers.new_base.modelaccessor
+
+        from sync_att_workflow_driver_service_instance import SyncAttWorkflowDriverServiceInstance, model_accessor
+
+        # import all class names to globals
+        for (k, v) in model_accessor.all_model_classes.items():
+            globals()[k] = v
+
+
+        self.sync_step = SyncAttWorkflowDriverServiceInstance
+
+        self.oss = Mock()
+        self.oss.name = "oss"
+        self.oss.id = 5367
+
+        # create a mock AttWorkflowDriverServiceInstance instance
+        self.o = Mock()
+        self.o.serial_number = "BRCM1234"
+        self.o.of_dpid = "of:109299321"
+        self.o.owner.leaf_model = self.oss
+        self.o.tologdict.return_value = {}
+
+    def tearDown(self):
+        self.o = None
+        sys.path = self.sys_path_save
+
+    def test_sync_valid(self):
+        with patch.object(AttWorkflowDriverWhiteListEntry.objects, "get_items") as whitelist_items:
+            # Create a whitelist entry for self.o's serial number
+            whitelist_entry = AttWorkflowDriverWhiteListEntry(owner_id=self.oss.id, serial_number=self.o.serial_number)
+            whitelist_items.return_value = [whitelist_entry]
+
+            self.sync_step().sync_record(self.o)
+
+            self.assertEqual(self.o.valid, "valid")
+            self.assertTrue(self.o.no_sync)
+            self.o.save.assert_called()
+
+    def test_sync_rejected(self):
+        self.sync_step().sync_record(self.o)
+
+        self.assertEqual(self.o.valid, "invalid")
+        self.assertTrue(self.o.no_sync)
+        self.o.save.assert_called()
+
+if __name__ == '__main__':
+    unittest.main()