diff --git a/faker/providers/phone_number/cs_CZ/__init__.py b/faker/providers/phone_number/cs_CZ/__init__.py
index ff5949c9fb..69b2363b6d 100644
--- a/faker/providers/phone_number/cs_CZ/__init__.py
+++ b/faker/providers/phone_number/cs_CZ/__init__.py
@@ -2,40 +2,30 @@
 
 
 class Provider(PhoneNumberProvider):
+
+    # Phone numbers
+    # https://cs.wikipedia.org/wiki/Telefonn%C3%AD_%C4%8D%C3%ADslo
+
     formats = (
-        "601 ### ###",
-        "603 ### ###",
-        "608 ### ###",
-        "790 ### ###",
-        "602 ### ###",
-        "604 ### ###",
-        "770 ### ###",
-        "606 ### ###",
-        "605 ### ###",
-        "773 ### ###",
-        "607 ### ###",
-        "730 ### ###",
-        "774 ### ###",
-        "702 ### ###",
-        "731 ### ###",
-        "775 ### ###",
-        "720 ### ###",
-        "732 ### ###",
-        "776 ### ###",
-        "721 ### ###",
-        "733 ### ###",
-        "777 ### ###",
-        "722 ### ###",
-        "734 ### ###",
-        "723 ### ###",
-        "736 ### ###",
-        "724 ### ###",
-        "737 ### ###",
-        "725 ### ###",
-        "738 ### ###",
-        "726 ### ###",
-        "739 ### ###",
-        "727 ### ###",
-        "728 ### ###",
-        "729 ### ###",
+        # 601-608
+        "+420 601 ### ###",
+        "+420 602 ### ###",
+        "+420 603 ### ###",
+        "+420 604 ### ###",
+        "+420 605 ### ###",
+        "+420 606 ### ###",
+        "+420 607 ### ###",
+        "+420 608 ### ###",
+        # 702-705
+        "+420 702 ### ###",
+        "+420 703 ### ###",
+        "+420 704 ### ###",
+        "+420 705 ### ###",
+        # 720-739
+        "+420 72# ### ###",
+        "+420 73# ### ###",
+        # 770-779
+        "+420 77# ### ###",
+        # 790-799
+        "+420 79# ### ###",
     )