diff --git a/VERSION b/VERSION
index 32f8572..a835adc 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-v3.8.1
+v3.8.2
diff --git a/adapters/AdapterInterface.php b/adapters/AdapterInterface.php
index 0371436..6521c0c 100644
--- a/adapters/AdapterInterface.php
+++ b/adapters/AdapterInterface.php
@@ -207,7 +207,7 @@ interface AdapterInterface
      *               ]
      *               ]
      */
-    public function inbound_call_callback(): array;
+    public static function inbound_call_callback(): array;
 
     /**
      * Method called on reception of a end call notification.
@@ -221,5 +221,5 @@ interface AdapterInterface
      *               ]
      *               ]
      */
-    public function end_call_callback(): array;
+    public static function end_call_callback(): array;
 }
diff --git a/adapters/BenchmarkAdapter.php b/adapters/BenchmarkAdapter.php
index 5d03ce3..ecb2216 100644
--- a/adapters/BenchmarkAdapter.php
+++ b/adapters/BenchmarkAdapter.php
@@ -259,12 +259,12 @@ namespace adapters;
             return true;
         }
 
-        public function inbound_call_callback(): array
+        public static function inbound_call_callback(): array
         {
             return [];
         }
 
-        public function end_call_callback(): array
+        public static function end_call_callback(): array
         {
             return [];
         }
diff --git a/adapters/GammuAdapter.php b/adapters/GammuAdapter.php
index eb4ff9f..cb42dd6 100644
--- a/adapters/GammuAdapter.php
+++ b/adapters/GammuAdapter.php
@@ -336,12 +336,12 @@ namespace adapters;
             return [];
         }
 
-        public function inbound_call_callback(): array
+        public static function inbound_call_callback(): array
         {
             return [];
         }
 
-        public function end_call_callback(): array
+        public static function end_call_callback(): array
         {
             return [];
         }
diff --git a/adapters/KannelAdapter.php b/adapters/KannelAdapter.php
index 19782d3..5e514b0 100644
--- a/adapters/KannelAdapter.php
+++ b/adapters/KannelAdapter.php
@@ -508,12 +508,12 @@ class KannelAdapter implements AdapterInterface
         return $response;
     }
 
-    public function inbound_call_callback(): array
+    public static function inbound_call_callback(): array
     {
         return [];
     }
 
-    public function end_call_callback(): array
+    public static function end_call_callback(): array
     {
         return [];
     }
diff --git a/adapters/OctopushShortcodeAdapter.php b/adapters/OctopushShortcodeAdapter.php
index 59283a5..340012c 100644
--- a/adapters/OctopushShortcodeAdapter.php
+++ b/adapters/OctopushShortcodeAdapter.php
@@ -486,12 +486,12 @@ class OctopushShortcodeAdapter implements AdapterInterface
         return $response;
     }
 
-    public function inbound_call_callback(): array
+    public static function inbound_call_callback(): array
     {
         return [];
     }
 
-    public function end_call_callback(): array
+    public static function end_call_callback(): array
     {
         return [];
     }
diff --git a/adapters/OctopushVirtualNumberAdapter.php b/adapters/OctopushVirtualNumberAdapter.php
index f9238a6..6822c66 100644
--- a/adapters/OctopushVirtualNumberAdapter.php
+++ b/adapters/OctopushVirtualNumberAdapter.php
@@ -479,12 +479,12 @@ class OctopushVirtualNumberAdapter implements AdapterInterface
         return $response;
     }
 
-    public function inbound_call_callback(): array
+    public static function inbound_call_callback(): array
     {
         return [];
     }
 
-    public function end_call_callback(): array
+    public static function end_call_callback(): array
     {
         return [];
     }
diff --git a/adapters/OdysseyMessagingAdapter.php b/adapters/OdysseyMessagingAdapter.php
index f48203c..5f7d7a3 100644
--- a/adapters/OdysseyMessagingAdapter.php
+++ b/adapters/OdysseyMessagingAdapter.php
@@ -499,12 +499,12 @@ class OdysseyMessagingAdapter implements AdapterInterface
         return $response;
     }
 
-    public function inbound_call_callback(): array
+    public static function inbound_call_callback(): array
     {
         return [];
     }
 
-    public function end_call_callback(): array
+    public static function end_call_callback(): array
     {
         return [];
     }
diff --git a/adapters/OvhSmsShortcodeAdapter.php b/adapters/OvhSmsShortcodeAdapter.php
index cf16795..5299bcd 100644
--- a/adapters/OvhSmsShortcodeAdapter.php
+++ b/adapters/OvhSmsShortcodeAdapter.php
@@ -406,12 +406,12 @@ namespace adapters;
             return [];
         }
 
-        public function inbound_call_callback(): array
+        public static function inbound_call_callback(): array
         {
             return [];
         }
 
-        public function end_call_callback(): array
+        public static function end_call_callback(): array
         {
             return [];
         }
diff --git a/adapters/OvhSmsVirtualNumberAdapter.php b/adapters/OvhSmsVirtualNumberAdapter.php
index cfc1b2a..36bae2f 100644
--- a/adapters/OvhSmsVirtualNumberAdapter.php
+++ b/adapters/OvhSmsVirtualNumberAdapter.php
@@ -396,12 +396,12 @@ namespace adapters;
             return [];
         }
 
-        public function inbound_call_callback(): array
+        public static function inbound_call_callback(): array
         {
             return [];
         }
 
-        public function end_call_callback(): array
+        public static function end_call_callback(): array
         {
             return [];
         }
diff --git a/adapters/TestAdapter.php b/adapters/TestAdapter.php
index 2ad3c48..e3181cb 100644
--- a/adapters/TestAdapter.php
+++ b/adapters/TestAdapter.php
@@ -351,7 +351,7 @@ namespace adapters;
             return [];
         }
 
-        public function inbound_call_callback(): array
+        public static function inbound_call_callback(): array
         {
             $response = [
                 'error' => false,
@@ -380,7 +380,7 @@ namespace adapters;
             return $response;
         }
 
-        public function end_call_callback(): array
+        public static function end_call_callback(): array
         {
             $response = [
                 'error' => false,
diff --git a/adapters/TwilioVirtualNumberAdapter.php b/adapters/TwilioVirtualNumberAdapter.php
index a17722c..c4ce67f 100644
--- a/adapters/TwilioVirtualNumberAdapter.php
+++ b/adapters/TwilioVirtualNumberAdapter.php
@@ -374,12 +374,12 @@ class TwilioVirtualNumberAdapter implements AdapterInterface
         return [];
     }
 
-    public function inbound_call_callback(): array
+    public static function inbound_call_callback(): array
     {
         return [];
     }
 
-    public function end_call_callback(): array
+    public static function end_call_callback(): array
     {
         return [];
     }