diff --git a/src/mms/inc_private/iso_client_connection.h b/src/mms/inc_private/iso_client_connection.h
index 1925cd2b..9a09b4f9 100644
--- a/src/mms/inc_private/iso_client_connection.h
+++ b/src/mms/inc_private/iso_client_connection.h
@@ -44,7 +44,7 @@ typedef enum
     ISO_IND_TICK
 } IsoIndication;
 
-typedef void*
+typedef bool
 (*IsoIndicationCallback)(IsoIndication indication, void* param, ByteBuffer* payload);
 
 /**
diff --git a/src/mms/iso_client/iso_client_connection.c b/src/mms/iso_client/iso_client_connection.c
index f5462265..5aa7f803 100644
--- a/src/mms/iso_client/iso_client_connection.c
+++ b/src/mms/iso_client/iso_client_connection.c
@@ -499,7 +499,9 @@ IsoClientConnection_handleConnection(IsoClientConnection self)
                            setState(self, STATE_CONNECTED);
                            nextState = INT_STATE_WAIT_FOR_DATA_MSG;
 
-                           self->callback(ISO_IND_ASSOCIATION_SUCCESS, self->callbackParameter, self->receivePayloadBuffer);
+                           if (self->callback(ISO_IND_ASSOCIATION_SUCCESS, self->callbackParameter, self->receivePayloadBuffer) == false) {
+                               nextState = INT_STATE_CLOSE_ON_ERROR;
+                           }
 
                            CotpConnection_resetPayload(self->cotpConnection);
                        }
diff --git a/src/mms/iso_mms/client/mms_client_connection.c b/src/mms/iso_mms/client/mms_client_connection.c
index e5d0d5e0..d88d3e15 100644
--- a/src/mms/iso_mms/client/mms_client_connection.c
+++ b/src/mms/iso_mms/client/mms_client_connection.c
@@ -981,7 +981,7 @@ handleAsyncResponse(MmsConnection self, ByteBuffer* response, uint32_t bufPos, M
         removeFromOutstandingCalls(self, outstandingCall->invokeId);
 }
 
-static void
+static bool
 mmsIsoCallback(IsoIndication indication, void* parameter, ByteBuffer* payload)
 {
     MmsConnection self = (MmsConnection) parameter;
@@ -1022,7 +1022,7 @@ mmsIsoCallback(IsoIndication indication, void* parameter, ByteBuffer* payload)
             }
         }
 
-        return;
+        return true;
     }
 
     if (indication == ISO_IND_CLOSED) {
@@ -1035,7 +1035,7 @@ mmsIsoCallback(IsoIndication indication, void* parameter, ByteBuffer* payload)
         if (self->connectionLostHandler != NULL)
             self->connectionLostHandler(self, self->connectionLostHandlerParameter);
 
-        return;
+        return true;
     }
 
     if (indication == ISO_IND_ASSOCIATION_FAILED) {
@@ -1043,12 +1043,12 @@ mmsIsoCallback(IsoIndication indication, void* parameter, ByteBuffer* payload)
             printf("MMS_CLIENT: mmsIsoCallback: association failed!\n");
 
         setConnectionState(self, MMS_CONNECTION_STATE_CLOSING);
-        return;
+        return false;
     }
 
     if (payload != NULL) {
         if (ByteBuffer_getSize(payload) < 1) {
-            return;
+            return false;
         }
     }
 
@@ -1075,7 +1075,8 @@ mmsIsoCallback(IsoIndication indication, void* parameter, ByteBuffer* payload)
             }
             else {
                 setConnectionState(self, MMS_CONNECTION_STATE_CLOSING);
-                IsoClientConnection_close(self->isoClient);
+
+                goto exit_with_error;
             }
         }
         else {
@@ -1083,8 +1084,19 @@ mmsIsoCallback(IsoIndication indication, void* parameter, ByteBuffer* payload)
 
             if (DEBUG_MMS_CLIENT)
                 printf("MMS_CLIENT: Failed to parse initiate response!\n");
+
+            return false;
         }
     }
+    else if (tag == 0xaa) { /* initiate error PDU */
+
+        if (DEBUG_MMS_CLIENT)
+              printf("MMS_CLIENT: received initiate error PDU\n");
+
+        setConnectionState(self, MMS_CONNECTION_STATE_CLOSING);
+
+        return false;
+    }
     else if (tag == 0xa3) { /* unconfirmed PDU */
         handleUnconfirmedMmsPdu(self, payload);
     }
@@ -1096,7 +1108,7 @@ mmsIsoCallback(IsoIndication indication, void* parameter, ByteBuffer* payload)
     }
     else if (tag == 0x8c) { /* conclude response PDU */
         if (DEBUG_MMS_CLIENT)
-            printf("MMS_CLIENT: received conclude.reponse+\n");
+            printf("MMS_CLIENT: received conclude.response+\n");
 
         if (self->concludeHandler) {
             self->concludeHandler(self->concludeHandlerParameter, MMS_ERROR_NONE, true);
@@ -1151,14 +1163,14 @@ mmsIsoCallback(IsoIndication indication, void* parameter, ByteBuffer* payload)
                     if (DEBUG_MMS_CLIENT)
                         printf("MMS_CLIENT: server sent unexpected confirmed error PDU!\n");
 
-                    return;
+                    return false;
                 }
             }
             else {
                 if (DEBUG_MMS_CLIENT)
                     printf("MMS_CLIENT: server sent confirmed error PDU without invoke ID!\n");
 
-                return;
+                return false;
             }
 
         }
@@ -1195,11 +1207,11 @@ mmsIsoCallback(IsoIndication indication, void* parameter, ByteBuffer* payload)
                     }
                 }
                 else {
-                    return;
+                    return false;
                 }
             }
             else {
-                return;
+                return false;
             }
 
         }
@@ -1247,7 +1259,7 @@ mmsIsoCallback(IsoIndication indication, void* parameter, ByteBuffer* payload)
                 if (DEBUG_MMS_CLIENT)
                     printf("MMS_CLIENT: unexpected message from server!\n");
 
-                return;
+                return false;
             }
         }
         else
@@ -1385,14 +1397,14 @@ mmsIsoCallback(IsoIndication indication, void* parameter, ByteBuffer* payload)
     if (DEBUG_MMS_CLIENT)
         printf("MMS_CLIENT: LEAVE mmsIsoCallback - OK\n");
 
-    return;
+    return true;
 
 exit_with_error:
 
     if (DEBUG_MMS_CLIENT)
         printf("MMS_CLIENT: received malformed message from server!\n");
 
-    return;
+    return false;
 }
 
 #if (CONFIG_MMS_THREADLESS_STACK == 0)