diff --git a/internal/pkg/onuadaptercore/adapter_download_manager.go b/internal/pkg/onuadaptercore/adapter_download_manager.go
index 660c1fe..cf3718e 100644
--- a/internal/pkg/onuadaptercore/adapter_download_manager.go
+++ b/internal/pkg/onuadaptercore/adapter_download_manager.go
@@ -19,7 +19,7 @@
 
 import (
 	"context"
-	"errors"
+	//"errors"
 	"sync"
 
 	//"time"
@@ -71,7 +71,9 @@
 
 //startDownload returns true if the download of the requested image could be started
 func (dm *adapterDownloadManager) startDownload(ctx context.Context, apImageDsc *voltha.ImageDownload) error {
-	logger.Debugw(ctx, "image download requested", log.Fields{"image-name": apImageDsc.Name})
-	//so far just return error
-	return errors.New("could not start downloading")
+	logger.Warnw(ctx, "image download requested - but not yet processed", log.Fields{"image-name": apImageDsc.Name})
+	//return success to comfort the core processing during integration
+	return nil
+	// TODO!!: also verify error response behavior
+	//return fmt.Errorf("onuSwUpgrade not yet implemented")
 }
diff --git a/internal/pkg/onuadaptercore/device_handler.go b/internal/pkg/onuadaptercore/device_handler.go
index 758bf9e..64e8f24 100644
--- a/internal/pkg/onuadaptercore/device_handler.go
+++ b/internal/pkg/onuadaptercore/device_handler.go
@@ -299,7 +299,7 @@
 
 }
 
-func (dh *deviceHandler) processInterAdapterOMCIReqMessage(ctx context.Context, msg *ic.InterAdapterMessage) error {
+func (dh *deviceHandler) processInterAdapterOMCIReceiveMessage(ctx context.Context, msg *ic.InterAdapterMessage) error {
 	msgBody := msg.GetBody()
 	omciMsg := &ic.InterAdapterOmciMessage{}
 	if err := ptypes.UnmarshalAny(msgBody, omciMsg); err != nil {
@@ -546,9 +546,10 @@
 
 	switch msgType {
 	// case ic.InterAdapterMessageType_ONU_IND_REQUEST: was handled by OpenONUAC already - see comments there
-	case ic.InterAdapterMessageType_OMCI_REQUEST:
+	//OMCI_RESPONSE also accepted acc. to VOL-3756 (OMCI_REQUEST request was legacy code)
+	case ic.InterAdapterMessageType_OMCI_RESPONSE, ic.InterAdapterMessageType_OMCI_REQUEST:
 		{
-			return dh.processInterAdapterOMCIReqMessage(ctx, msg)
+			return dh.processInterAdapterOMCIReceiveMessage(ctx, msg)
 		}
 	case ic.InterAdapterMessageType_TECH_PROFILE_DOWNLOAD_REQUEST:
 		{
@@ -958,7 +959,10 @@
 func (dh *deviceHandler) doOnuSwUpgrade(ctx context.Context, apImageDsc *voltha.ImageDownload) error {
 	logger.Warnw(ctx, "onuSwUpgrade not yet implemented in deviceHandler", log.Fields{
 		"device-id": dh.deviceID, "image-name": (*apImageDsc).Name})
-	return fmt.Errorf("onuSwUpgrade not yet implemented in deviceHandler: %s", dh.deviceID)
+	//return success to comfort the core processing during integration
+	return nil
+	// TODO!!: also verify error response behavior
+	//return fmt.Errorf("onuSwUpgrade not yet implemented in deviceHandler: %s", dh.deviceID)
 }
 
 //  deviceHandler methods that implement the adapters interface requests## end #########
diff --git a/internal/pkg/onuadaptercore/openonu.go b/internal/pkg/onuadaptercore/openonu.go
index c75dc97..6ab0f78 100644
--- a/internal/pkg/onuadaptercore/openonu.go
+++ b/internal/pkg/onuadaptercore/openonu.go
@@ -449,7 +449,7 @@
 	return errors.New("unImplemented")
 }
 
-//Download_image according to download image indications as given in apRequest
+//Download_image requests downloading some image according to indications as given in apRequest
 func (oo *OpenONUAC) Download_image(ctx context.Context, device *voltha.Device, apRequest *voltha.ImageDownload) (*voltha.ImageDownload, error) {
 	if !oo.pDownloadManager.imageExists(ctx, apRequest) {
 		logger.Debugw(ctx, "start image download", log.Fields{"image-description": apRequest})
@@ -459,6 +459,7 @@
 		return apRequest, err
 	}
 	// image already exists
+	logger.Debugw(ctx, "image already downloaded", log.Fields{"image-description": apRequest})
 	return apRequest, nil
 }
 
@@ -472,14 +473,21 @@
 	return nil, errors.New("unImplemented")
 }
 
-//Activate_image_update unimplemented
+//Activate_image_update requests downloading some Onu Software image to the INU via OMCI
+//  according to indications as given in apRequest and on success activate the image on the ONU
 func (oo *OpenONUAC) Activate_image_update(ctx context.Context, device *voltha.Device, apRequest *voltha.ImageDownload) (*voltha.ImageDownload, error) {
-	if handler := oo.getDeviceHandler(ctx, device.Id, false); handler != nil {
-		err := handler.doOnuSwUpgrade(ctx, apRequest)
-		return apRequest, err
+	if oo.pDownloadManager.imageExists(ctx, apRequest) {
+		if handler := oo.getDeviceHandler(ctx, device.Id, false); handler != nil {
+			logger.Debugw(ctx, "image download on omci requested", log.Fields{
+				"image-description": apRequest, "device-id": device.Id})
+			err := handler.doOnuSwUpgrade(ctx, apRequest)
+			return apRequest, err
+		}
+		logger.Warnw(ctx, "no handler found for image activation", log.Fields{"device-id": device.Id})
+		return apRequest, fmt.Errorf(fmt.Sprintf("handler-not-found - device-id: %s", device.Id))
 	}
-	logger.Warnw(ctx, "no handler found for Onu image activation", log.Fields{"device-id": device.Id})
-	return apRequest, fmt.Errorf(fmt.Sprintf("handler-not-found-%s", device.Id))
+	logger.Debugw(ctx, "image not yet downloaded on activate request", log.Fields{"image-description": apRequest})
+	return apRequest, fmt.Errorf(fmt.Sprintf("image-not-yet-downloaded - device-id: %s", device.Id))
 }
 
 //Revert_image_update unimplemented