diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7d744c29e..779792126 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -26,6 +26,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ### Changed
 - Chipset: use da145xx in folder/file/function names for these SoCs
+- ATT Server: use uint8_t for status returns
 - AVDTP: use BLUETOOTH_SERVICE_CLASS_AUDIO_SINK / SOURCE instead of BLUETOOTH_PROTOCOL_AVDTP in SDP queries
 
 ## Release v1.5.1
diff --git a/src/ble/att_server.c b/src/ble/att_server.c
index 0fbddce24..0f136da91 100644
--- a/src/ble/att_server.c
+++ b/src/ble/att_server.c
@@ -599,7 +599,7 @@ static int att_server_process_validated_request(hci_connection_t * hci_connectio
 }
 
 #ifdef ENABLE_ATT_DELAYED_RESPONSE
-int att_server_response_ready(hci_con_handle_t con_handle){
+uint8_t att_server_response_ready(hci_con_handle_t con_handle){
     hci_connection_t * hci_connection = hci_connection_for_handle(con_handle);
     if (!hci_connection) return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
     att_server_t * att_server = &hci_connection->att_server;
@@ -1191,7 +1191,7 @@ int  att_server_can_send_packet_now(hci_con_handle_t con_handle){
     return att_server_can_send_packet(hci_connection);
 }
 
-int att_server_register_can_send_now_callback(btstack_context_callback_registration_t * callback_registration, hci_con_handle_t con_handle){
+uint8_t att_server_register_can_send_now_callback(btstack_context_callback_registration_t * callback_registration, hci_con_handle_t con_handle){
     return att_server_request_to_send_notification(callback_registration, con_handle);
 }
 
@@ -1201,7 +1201,7 @@ void att_server_request_can_send_now_event(hci_con_handle_t con_handle){
 }
 // end of deprecated
 
-int att_server_request_to_send_notification(btstack_context_callback_registration_t * callback_registration, hci_con_handle_t con_handle){
+uint8_t att_server_request_to_send_notification(btstack_context_callback_registration_t * callback_registration, hci_con_handle_t con_handle){
     hci_connection_t * hci_connection = hci_connection_for_handle(con_handle);
     if (!hci_connection) return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
     att_server_t * att_server = &hci_connection->att_server;
@@ -1214,7 +1214,7 @@ int att_server_request_to_send_notification(btstack_context_callback_registratio
     }
 }
 
-int att_server_request_to_send_indication(btstack_context_callback_registration_t * callback_registration, hci_con_handle_t con_handle){
+uint8_t att_server_request_to_send_indication(btstack_context_callback_registration_t * callback_registration, hci_con_handle_t con_handle){
     hci_connection_t * hci_connection = hci_connection_for_handle(con_handle);
     if (!hci_connection) return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
     att_server_t * att_server = &hci_connection->att_server;
@@ -1227,7 +1227,7 @@ int att_server_request_to_send_indication(btstack_context_callback_registration_
     }
 }
 
-int att_server_notify(hci_con_handle_t con_handle, uint16_t attribute_handle, const uint8_t *value, uint16_t value_len){
+uint8_t att_server_notify(hci_con_handle_t con_handle, uint16_t attribute_handle, const uint8_t *value, uint16_t value_len){
     hci_connection_t * hci_connection = hci_connection_for_handle(con_handle);
     if (!hci_connection) return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
     att_connection_t * att_connection = &hci_connection->att_connection;
@@ -1246,7 +1246,7 @@ int att_server_notify(hci_con_handle_t con_handle, uint16_t attribute_handle, co
 	return l2cap_send_prepared_connectionless(att_connection->con_handle, L2CAP_CID_ATTRIBUTE_PROTOCOL, size);
 }
 
-int att_server_indicate(hci_con_handle_t con_handle, uint16_t attribute_handle, const uint8_t *value, uint16_t value_len){
+uint8_t att_server_indicate(hci_con_handle_t con_handle, uint16_t attribute_handle, const uint8_t *value, uint16_t value_len){
     hci_connection_t * hci_connection = hci_connection_for_handle(con_handle);
     if (!hci_connection) return ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER;
     att_server_t * att_server = &hci_connection->att_server;
diff --git a/src/ble/att_server.h b/src/ble/att_server.h
index c0b0d0225..cba5ee8ef 100644
--- a/src/ble/att_server.h
+++ b/src/ble/att_server.h
@@ -83,7 +83,7 @@ void att_server_register_service_handler(att_service_handler_t * handler);
  * @param con_handle
  * @return 0 if ok, error otherwise
  */
-int att_server_register_can_send_now_callback(btstack_context_callback_registration_t * callback_registration, hci_con_handle_t con_handle);
+uint8_t att_server_register_can_send_now_callback(btstack_context_callback_registration_t * callback_registration, hci_con_handle_t con_handle);
 
 /**
  * @brief Return ATT MTU
@@ -99,7 +99,7 @@ uint16_t att_server_get_mtu(hci_con_handle_t con_handle);
  * @param con_handle
  * @return ERROR_CODE_SUCCESS if ok, ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER if handle unknown, and ERROR_CODE_COMMAND_DISALLOWED if callback already registered
  */
-int att_server_request_to_send_notification(btstack_context_callback_registration_t * callback_registration, hci_con_handle_t con_handle);
+uint8_t att_server_request_to_send_notification(btstack_context_callback_registration_t * callback_registration, hci_con_handle_t con_handle);
 
 /**
  * @brief Request callback when sending indication is possible
@@ -108,7 +108,7 @@ int att_server_request_to_send_notification(btstack_context_callback_registratio
  * @param con_handle
  * @return ERROR_CODE_SUCCESS if ok, ERROR_CODE_UNKNOWN_CONNECTION_IDENTIFIER if handle unknown, and ERROR_CODE_COMMAND_DISALLOWED if callback already registered
  */
-int att_server_request_to_send_indication(btstack_context_callback_registration_t * callback_registration, hci_con_handle_t con_handle);
+uint8_t att_server_request_to_send_indication(btstack_context_callback_registration_t * callback_registration, hci_con_handle_t con_handle);
 
 /*
  * @brief notify client about attribute value change
@@ -118,7 +118,7 @@ int att_server_request_to_send_indication(btstack_context_callback_registration_
  * @param value_len
  * @return 0 if ok, error otherwise
  */
-int att_server_notify(hci_con_handle_t con_handle, uint16_t attribute_handle, const uint8_t *value, uint16_t value_len);
+uint8_t att_server_notify(hci_con_handle_t con_handle, uint16_t attribute_handle, const uint8_t *value, uint16_t value_len);
 
 /*
  * @brief indicate value change to client. client is supposed to reply with an indication_response
@@ -128,7 +128,7 @@ int att_server_notify(hci_con_handle_t con_handle, uint16_t attribute_handle, co
  * @param value_len
  * @return 0 if ok, error otherwise
  */
-int att_server_indicate(hci_con_handle_t con_handle, uint16_t attribute_handle, const uint8_t *value, uint16_t value_len);
+uint8_t att_server_indicate(hci_con_handle_t con_handle, uint16_t attribute_handle, const uint8_t *value, uint16_t value_len);
 
 #ifdef ENABLE_ATT_DELAYED_RESPONSE
 /*
@@ -138,7 +138,7 @@ int att_server_indicate(hci_con_handle_t con_handle, uint16_t attribute_handle,
  * @param con_handle
  * @return 0 if ok, error otherwise
  */
-int att_server_response_ready(hci_con_handle_t con_handle);
+uint8_t att_server_response_ready(hci_con_handle_t con_handle);
 #endif
 
 // the following functions will be removed soon