diff --git a/xos/synchronizer/helpers.py b/xos/synchronizer/helpers.py
new file mode 100644
index 0000000..7d66e8f
--- /dev/null
+++ b/xos/synchronizer/helpers.py
@@ -0,0 +1,171 @@
+# Copyright 2020-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 xossynchronizer.steps.syncstep import DeferredException
+import time
+import requests
+from requests.auth import HTTPBasicAuth
+
+class NttHelpers():
+    @staticmethod
+    def validate_onu(model_accessor, log, ntt_si):
+        """
+        This method validate an ONU against the whitelist and set the appropriate state.
+        It's expected that the deferred exception is managed in the caller method,
+        for example a model_policy or a sync_step.
+
+        :param ntt_si: NttWorkflowDriverServiceInstance
+        :return: [boolean, string]
+        """
+        tech_value = json.loads(model_accessor.TechnologyProfile.objects.get(profile_id=64).profile_value)
+        if tech_value["profile_type"] == "EPON":
+            tech = tech_value["epon_attribute"]["package_type"]
+        else:
+            tech = tech_value["profile_type"]
+              
+        oss_service = ntt_si.owner.leaf_model
+
+        # See if there is a matching entry in the whitelist.
+        matching_entries = model_accessor.NttWorkflowDriverWhiteListEntry.objects.filter(
+            owner_id=oss_service.id,
+        )
+        
+        matching_entries = [e for e in matching_entries if e.mac_address.lower() == ntt_si.mac_address.lower()]
+        
+        if len(matching_entries) == 0:
+            log.warn("ONU not found in whitelist")
+            return [False, "ONU not found in whitelist"]
+
+        whitelisted = matching_entries[0]
+        try:
+            onu = model_accessor.ONUDevice.objects.get(serial_number=ntt_si.serial_number.split("-")[0])
+            pon_port = onu.pon_port
+        except IndexError:
+            raise DeferredException("ONU device %s is not know to XOS yet" % ntt_si.serial_number)
+
+        if onu.admin_state == "ADMIN_DISABLED":
+            return [False, "ONU has been manually disabled"]
+
+        if pon_port.port_no < whitelisted.pon_port_from or pon_port.port_no > whitelisted.pon_port_to:
+            log.warn("PON port is not approved.")
+            return [False, "PON port is not approved."]
+        
+        if tech == "B":
+            if ntt_si.authentication_state == "DENIED":
+                return [False, "IEEE802.1X authentication has not been denied."]
+            elif ntt_si.authentication_state != "APPROVED":
+                return [True, "IEEE802.1X authentication has not been done yet."]
+        else:
+            pass
+
+        log.debug("Adding subscriber with info",
+            uni_port_id = ntt_si.uni_port_id,
+            dp_id = ntt_si.of_dpid
+        )
+        
+        time.sleep(180)
+
+        onos_voltha_basic_auth = HTTPBasicAuth("karaf", "karaf")
+
+        handle = "%s/%s" % (ntt_si.of_dpid, ntt_si.uni_port_id)
+        # TODO store URL and PORT in the vOLT Service model
+        full_url = "http://129.60.110.180:8181/onos/olt/oltapp/%s" % (handle)
+
+        log.info("Sending request to onos-voltha", url=full_url)
+
+        request = requests.post(full_url, auth=onos_voltha_basic_auth)
+
+        if request.status_code != 200:
+            raise Exception("Failed to add subscriber in onos-voltha: %s" % request.text)
+        log.info("Added Subscriber in onos voltha", response=request.text)
+
+        return [True, "ONU has been validated"]
+
+    @staticmethod
+    def find_or_create_ntt_si(model_accessor, log, event):
+        try:
+            ntt_si = model_accessor.NttWorkflowDriverServiceInstance.objects.get(
+                serial_number=event["serialNumber"]
+            )
+            try:
+                onu = model_accessor.ONUDevice.objects.get(serial_number=event["serialNumber"].split("-")[0])
+                ntt_si.mac_address = onu.mac_address
+            except IndexError:
+                log.debug("NttHelpers: ONU has been deleted", si=ntt_si)
+            log.debug("NttHelpers: Found existing NttWorkflowDriverServiceInstance", si=ntt_si)
+        except IndexError:
+            # create an NttWorkflowDriverServiceInstance, the validation will be
+            # triggered in the corresponding sync step
+            while True:
+                try:
+                    onu = model_accessor.ONUDevice.objects.get(serial_number=event["serialNumber"].split("-")[0])
+                    break
+                except IndexError:
+                    time.sleep(1)
+                    continue
+
+            ntt_si = model_accessor.NttWorkflowDriverServiceInstance(
+                serial_number=event["serialNumber"],
+                of_dpid=event["deviceId"],
+                uni_port_id=long(event["portNumber"]),
+                mac_address=onu.mac_address,
+                # we assume there is only one NttWorkflowDriverService
+                owner=model_accessor.NttWorkflowDriverService.objects.first()
+            )
+            log.debug("NttHelpers: Created new NttWorkflowDriverServiceInstance", si=ntt_si)
+        return ntt_si
+
+    @staticmethod
+    def find_or_create_ntt_oi(model_accessor, log, event):
+        try:
+            ntt_oi = model_accessor.NttWorkflowDriverOltInformation.objects.get(
+                of_dpid=event["deviceId"]
+            )
+            try:
+                onu = model_accessor.ONUDevice.objects.get(serial_number=event["serialNumber"].split("-")[0])
+                ntt_oi.port_no = onu.pon_port.port_no
+                tech_value = json.loads(model_accessor.TechnologyProfile.objects.get(profile_id=64).profile_value)
+                if tech_value["profile_type"] == "EPON":
+                    tech = tech_value["epon_attribute"]["package_type"]
+                else:
+                    tech = tech_value["profile_type"]
+                ntt_oi.olt_package = tech
+            except IndexError:
+                log.debug("NttHelpers: ONU has been deleted", oi=ntt_oi)
+            log.debug("NttHelpers: Found existing NttWorkflowDriverOltInformation", oi=ntt_oi)
+        except IndexError:
+            while True:
+                try:
+                    onu = model_accessor.ONUDevice.objects.get(serial_number=event["serialNumber"].split("-")[0])
+                    break
+                except IndexError:
+                    time.sleep(1)
+                    continue
+
+            tech_value = json.loads(model_accessor.TechnologyProfile.objects.get(profile_id=64).profile_value)
+            if tech_value["profile_type"] == "EPON":
+                tech = tech_value["epon_attribute"]["package_type"]
+            else:
+                tech = tech_value["profile_type"]
+
+            pon_port = onu.pon_port
+            ntt_oi = model_accessor.NttWorkflowDriverOltInformation(
+                of_dpid=event["deviceId"],
+                olt_package=tech,
+                port_no=pon_port.port_no,
+                owner=model_accessor.NttWorkflowDriverService.objects.first()
+            )
+            log.debug("NttHelpers: Created new NttWorkflowDriverOltInformation", oi=ntt_oi)
+        return ntt_oi
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