diff --git a/fieldpoc/dect.py b/fieldpoc/dect.py
index 4fc5352..32508fd 100644
--- a/fieldpoc/dect.py
+++ b/fieldpoc/dect.py
@@ -31,6 +31,11 @@ class Dect:
     def get_sip_password_for_number(self, num):
         return num
 
+    def create_and_bind_user(self, d, num):
+        u = self.c.create_user(num)
+        self.c.attach_user_device(u.uid, d.ppn)
+        self.c.set_user_relation_fixed(u.uid)
+        self.c.set_user_sipauth(u.uid, num, self.get_sip_password_for_number(num))
 
     def run(self):
         logger.info("initialising connection to OMM")
@@ -43,13 +48,57 @@ class Dect:
             if msg.get("type") == "stop":
                 break
             elif msg.get("type") == "sync":
-                unbound_devices = self.c.find_devices(lambda d: d.relType == mitel_ommclient2.types.PPRelTypeType("Unbound"))
+                logger.info("syncing")
 
-                for d in unbound_devices:
-                    print(d)
-                    temp_num = self.get_temp_number()
-                    u = self.c.create_user(temp_num)
-                    print(u)
-                    self.c.attach_user_device(u.uid, d.ppn)
-                    self.c.set_user_relation_fixed(u.uid)
-                    self.c.set_user_sipauth(u.uid, temp_num, self.get_sip_password_for_number(temp_num))
+                extensions = self.fp.extensions.extensions_by_type("dect")
+                extensions_by_num = {e.num: e for e in extensions}
+                extensions_by_ipei = {e._c['dect_ipei']: e for _, e in extensions_by_num.items() if e._c.get('dect_ipei')}
+
+                users_by_ext = {}
+                users_by_uid = {}
+                for user in self.c.get_users():
+                    e = extensions_by_num.get(user.num)
+                    if not e:
+                        # user in omm, but not as dect in nerd
+                        # TODO: delete in omm
+                        if user.num.startswith(next(self.fp.extensions.extensions_by_type("temp")).num):
+                            users_by_ext[user.num] = user
+                            users_by_uid[user.uid] = user
+                        continue
+                    elif e._c['name'] != user.name:
+                        self.c.set_user_name(user.uid, e._c['name'])
+                    if e._c.get('dect_ipei') and user.relType != mitel_ommclient2.types.PPRelTypeType("Unbound"):
+                        d = self.c.get_device(user.ppn)
+                        if d.ipei != e._c['dect_ipei']:
+                            logger.debug(f"Detaching {user} {d}")
+                            self.c.detach_user_device(user.uid, user.ppn)
+
+                    self.c.set_user_sipauth(user.uid, e.num, self.get_sip_password_for_number(e.num))
+                    users_by_ext[user.num] = user
+                    users_by_uid[user.uid] = user
+
+                for d in self.c.get_devices():
+                    e = extensions_by_ipei.get(d.ipei)
+                    if e:
+                        # device is in nerd
+                        u = users_by_ext.get(e.num)
+                        if u and d.relType == mitel_ommclient2.types.PPRelTypeType("Unbound"):
+                            logger.debug(f'Binding user for {d}')
+                            self.c.attach_user_device(u.uid, d.ppn)
+                            self.c.set_user_relation_fixed(u.uid)
+                        elif d.relType != mitel_ommclient2.types.PPRelTypeType("Unbound"):
+                            ui = users_by_uid.get(d.uid)
+                            if ui.num != e.num:
+                                logger.debug(f'User for {d} has wrong number')
+                                self.c.set_user_num(d.uid, e.num)
+                                self.c.set_user_sipauth(d.uid, e.num, self.get_sip_password_for_number(e.num))
+                        else:
+                            logger.debug(f'Creating and binding user for {d}')
+                            self.create_and_bind_user(d, e.num)
+
+                    elif d.relType == mitel_ommclient2.types.PPRelTypeType("Unbound"):
+                        temp_num = self.get_temp_number()
+                        logger.debug(f'Creating and binding tmp-user for {d}: {temp_num}')
+                        self.create_and_bind_user(d, temp_num)
+
+        self.c.connection.close()