diff --git a/README.md b/README.md
index ec23f15..b13420b 100644
--- a/README.md
+++ b/README.md
@@ -38,8 +38,11 @@ in [Edit Configuration](edit-configuration). When it is enabled - this integrati
 for every additional tracked flight from `sensor.flightradar24_additional_tracked`.
 
 To create device_tracker for a flight:
-1. Add a flight to Additional tracked by flight number
-2. Use device_tracker `device_tracker.FLIGHT_NUMBER`.
+1. Add a flight to Additional tracked by flight number. If it has no flight number, use callsign
+2. Use device_tracker `device_tracker.FLIGHT_NUMBER` if flight number exists or `device_tracker.CALL_SIGN`.
+
+To find device_tracker - Go to `Developer tools` and search for your flight number or callsign - you’ll find sensor
+like `device_tracker.FLIGHT_NUMBER` or `device_tracker.CALL_SIGN`.
 
 ### Configuration
  - Add to track
diff --git a/custom_components/flightradar24/device_tracker.py b/custom_components/flightradar24/device_tracker.py
index 6c5c6ae..6039c88 100644
--- a/custom_components/flightradar24/device_tracker.py
+++ b/custom_components/flightradar24/device_tracker.py
@@ -38,12 +38,13 @@ def update_items(
     new_tracked: list[FlightRadar24Tracker] = []
     active: list[str] = []
     for flight in coordinator.tracked.values():
-        active.append(flight['flight_number'])
-        if flight['flight_number'] not in tracked:
-            tracked[flight['flight_number']] = FlightRadar24Tracker(coordinator, flight)
-            new_tracked.append(tracked[flight['flight_number']])
+        flight_id = flight['flight_number'] if flight['flight_number'] else flight['callsign']
+        active.append(flight_id)
+        if flight_id not in tracked:
+            tracked[flight_id] = FlightRadar24Tracker(coordinator, flight)
+            new_tracked.append(tracked[flight_id])
         else:
-            tracked[flight['flight_number']].info = flight
+            tracked[flight_id].info = flight
 
     if new_tracked:
         async_add_entities(new_tracked)
diff --git a/custom_components/flightradar24/manifest.json b/custom_components/flightradar24/manifest.json
index 53c6dcf..d1f351b 100644
--- a/custom_components/flightradar24/manifest.json
+++ b/custom_components/flightradar24/manifest.json
@@ -7,5 +7,5 @@
     "iot_class": "cloud_polling",
     "issue_tracker": "https://github.com/AlexandrErohin/home-assistant-flightradar24/issues",
     "requirements": ["FlightRadarAPI==1.3.34", "pycountry==23.12.11"],
-    "version": "1.21.0"
+    "version": "1.21.1"
 }
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