diff --git a/pkg/control/e2ap.go b/pkg/control/e2ap.go
index f9580d9..8f9f7c9 100644
--- a/pkg/control/e2ap.go
+++ b/pkg/control/e2ap.go
@@ -27,139 +27,144 @@
 import "C"
 
 import (
-	"errors"
 	"unsafe"
+	"fmt"
 )
 
 type E2ap struct {
 }
 
+/* RICsubscriptionRequest */
+
+// Used by e2t test stub
 func (c *E2ap) GetSubscriptionRequestSequenceNumber(payload []byte) (subId uint16, err error) {
 	cptr := unsafe.Pointer(&payload[0])
 	cret := C.e2ap_get_ric_subscription_request_sequence_number(cptr, C.size_t(len(payload)))
 	if cret < 0 {
-		return 0, errors.New("e2ap wrapper is unable to get Subscirption Request Sequence Number due to wrong or invalid payload")
+		return 0, fmt.Errorf("e2ap wrapper is unable to get Subscirption Request Sequence Number due to wrong or invalid payload. ErrorCode: %v",cret)
 	}
 	subId = uint16(cret)
 	return
 }
 
-func (c *E2ap) SetSubscriptionRequestSequenceNumber(payload []byte, newSubscriptionid uint16) (newPayload []byte, err error) {
+// Used by submgr, rco test stub
+func (c *E2ap) SetSubscriptionRequestSequenceNumber(payload []byte, newSubscriptionid uint16) (err error) {
 	cptr := unsafe.Pointer(&payload[0])
 	size := C.e2ap_set_ric_subscription_request_sequence_number(cptr, C.size_t(len(payload)), C.long(newSubscriptionid))
 	if size < 0 {
-		return make([]byte, 0), errors.New("e2ap wrapper is unable to set Subscription Request Sequence Number due to wrong or invalid payload")
+		return fmt.Errorf("e2ap wrapper is unable to set Subscription Request Sequence Number due to wrong or invalid payload. ErrorCode: %v",size)
 	}
-	newPayload = C.GoBytes(cptr, C.int(size))
 	return
 }
 
+// Used by submgr, rco test stub
 func (c *E2ap) GetSubscriptionResponseSequenceNumber(payload []byte) (subId uint16, err error) {
 	cptr := unsafe.Pointer(&payload[0])
 	cret := C.e2ap_get_ric_subscription_response_sequence_number(cptr, C.size_t(len(payload)))
 	if cret < 0 {
-		return 0, errors.New("e2ap wrapper is unable to get Subscirption Response Sequence Number due to wrong or invalid payload")
+		return 0, fmt.Errorf("e2ap wrapper is unable to get Subscirption Response Sequence Number due to wrong or invalid payload. ErrorCode: %v",cret)
 	}
 	subId = uint16(cret)
 	return
 }
 
-func (c *E2ap) SetSubscriptionResponseSequenceNumber(payload []byte, newSubscriptionid uint16) (newPayload []byte, err error) {
+// Used by e2t test stub
+func (c *E2ap) SetSubscriptionResponseSequenceNumber(payload []byte, newSubscriptionid uint16) (err error)  {
 	cptr := unsafe.Pointer(&payload[0])
 	size := C.e2ap_set_ric_subscription_response_sequence_number(cptr, C.size_t(len(payload)), C.long(newSubscriptionid))
 	if size < 0 {
-		return make([]byte, 0), errors.New("e2ap wrapper is unable to set Subscription Response Sequence Number due to wrong or invalid payload")
+		return fmt.Errorf("e2ap wrapper is unable to set Subscription Response Sequence Number due to wrong or invalid payload. ErrorCode: %v",size)
 	}
-	newPayload = C.GoBytes(cptr, C.int(size))
 	return
 }
 
 /* RICsubscriptionDeleteRequest */
 
+// Used by submgr, e2t test stub
 func (c *E2ap) GetSubscriptionDeleteRequestSequenceNumber(payload []byte) (subId uint16, err error) {
 	cptr := unsafe.Pointer(&payload[0])
 	cret := C.e2ap_get_ric_subscription_delete_request_sequence_number(cptr, C.size_t(len(payload)))
 	if cret < 0 {
-		return 0, errors.New("e2ap wrapper is unable to get Subscirption Delete Request Sequence Number due to wrong or invalid payload")
+		return 0, fmt.Errorf("e2ap wrapper is unable to get Subscirption Delete Request Sequence Number due to wrong or invalid payload. ErrorCode: %v",cret)
 	}
 	subId = uint16(cret)
 	return
 }
 
-func (c *E2ap) SetSubscriptionDeleteRequestSequenceNumber(payload []byte, newSubscriptionid uint16) (newPayload []byte, err error) {
+// Used by rco test stub
+func (c *E2ap) SetSubscriptionDeleteRequestSequenceNumber(payload []byte, newSubscriptionid uint16) (err error)  {
 	cptr := unsafe.Pointer(&payload[0])
 	size := C.e2ap_set_ric_subscription_delete_request_sequence_number(cptr, C.size_t(len(payload)), C.long(newSubscriptionid))
 	if size < 0 {
-		return make([]byte, 0), errors.New("e2ap wrapper is unable to set Subscription Delete Request Sequence Number due to wrong or invalid payload")
+		return fmt.Errorf("e2ap wrapper is unable to set Subscription Delete Request Sequence Number due to wrong or invalid payload. ErrorCode: %v",size)
 	}
-	newPayload = C.GoBytes(cptr, C.int(size))
 	return
 }
 
 /* RICsubscriptionDeleteResponse */
 
+// Used by submgr, rco test stub
 func (c *E2ap) GetSubscriptionDeleteResponseSequenceNumber(payload []byte) (subId uint16, err error) {
 	cptr := unsafe.Pointer(&payload[0])
 	cret := C.e2ap_get_ric_subscription_delete_response_sequence_number(cptr, C.size_t(len(payload)))
 	if cret < 0 {
-		return 0, errors.New("e2ap wrapper is unable to get Subscirption Delete Response Sequence Number due to wrong or invalid payload")
+		return 0, fmt.Errorf("e2ap wrapper is unable to get Subscirption Delete Response Sequence Number due to wrong or invalid payload. ErrorCode: %v",cret)
 	}
 	subId = uint16(cret)
 	return
 }
 
-func (c *E2ap) SetSubscriptionDeleteResponseSequenceNumber(payload []byte, newSubscriptionid uint16) (newPayload []byte, err error) {
+// Used by e2t test stub
+func (c *E2ap) SetSubscriptionDeleteResponseSequenceNumber(payload []byte, newSubscriptionid uint16) (err error)  {
 	cptr := unsafe.Pointer(&payload[0])
 	size := C.e2ap_set_ric_subscription_delete_response_sequence_number(cptr, C.size_t(len(payload)), C.long(newSubscriptionid))
 	if size < 0 {
-		return make([]byte, 0), errors.New("e2ap wrapper is unable to set Subscription Delete Response Sequence Number due to wrong or invalid payload")
+		return fmt.Errorf("e2ap wrapper is unable to set Subscription Delete Response Sequence Number due to wrong or invalid payload. ErrorCode: %v",size)
 	}
-	newPayload = C.GoBytes(cptr, C.int(size))
 	return
 }
 
 /* RICsubscriptionRequestFailure */
 
+// Used by submgr
 func (c *E2ap) GetSubscriptionFailureSequenceNumber(payload []byte) (subId uint16, err error) {
 	cptr := unsafe.Pointer(&payload[0])
 	cret := C.e2ap_get_ric_subscription_failure_sequence_number(cptr, C.size_t(len(payload)))
 	if cret < 0 {
-		return 0, errors.New("e2ap wrapper is unable to get Subscirption Failure Sequence Number due to wrong or invalid payload")
+		return 0, fmt.Errorf("e2ap wrapper is unable to get Subscirption Failure Sequence Number due to wrong or invalid payload. ErrorCode: %v",cret)
 	}
 	subId = uint16(cret)
 	return
 }
 
-// This function is not used currently. Can be deleted if not needed
-func (c *E2ap) SetSubscriptionFailureSequenceNumber(payload []byte, newSubscriptionid uint16) (newPayload []byte, err error) {
+// Used by submgr
+func (c *E2ap) SetSubscriptionFailureSequenceNumber(payload []byte, newSubscriptionid uint16) (err error)  {
 	cptr := unsafe.Pointer(&payload[0])
 	size := C.e2ap_set_ric_subscription_failure_sequence_number(cptr, C.size_t(len(payload)), C.long(newSubscriptionid))
 	if size < 0 {
-		return make([]byte, 0), errors.New("e2ap wrapper is unable to set Subscription Failure Sequence Number due to wrong or invalid payload")
+		return fmt.Errorf("e2ap wrapper is unable to set Subscription Failure Sequence Number due to wrong or invalid payload. ErrorCode: %v",size)
 	}
-	newPayload = C.GoBytes(cptr, C.int(size))
 	return
 }
 
 /* RICsubscriptionDeleteFailure */
 
+// Used by submgr
 func (c *E2ap) GetSubscriptionDeleteFailureSequenceNumber(payload []byte) (subId uint16, err error) {
 	cptr := unsafe.Pointer(&payload[0])
 	cret := C.e2ap_get_ric_subscription_delete_failure_sequence_number(cptr, C.size_t(len(payload)))
 	if cret < 0 {
-		return 0, errors.New("e2ap wrapper is unable to get Subscirption Delete Failure Sequence Number due to wrong or invalid payload")
+		return 0, fmt.Errorf("e2ap wrapper is unable to get Subscirption Delete Failure Sequence Number due to wrong or invalid payload. ErrorCode: %v",cret)
 	}
 	subId = uint16(cret)
 	return
 }
-
-// This function is not used currently. Can be deleted if not needed
-func (c *E2ap) SetSubscriptionDeleteFailureSequenceNumber(payload []byte, newSubscriptionid uint16) (newPayload []byte, err error) {
+// Used by submgr
+func (c *E2ap) SetSubscriptionDeleteFailureSequenceNumber(payload []byte, newSubscriptionid uint16) (err error)  {
 	cptr := unsafe.Pointer(&payload[0])
 	size := C.e2ap_set_ric_subscription_delete_failure_sequence_number(cptr, C.size_t(len(payload)), C.long(newSubscriptionid))
 	if size < 0 {
-		return make([]byte, 0), errors.New("e2ap wrapper is unable to set Subscription Delete Failure Sequence Number due to wrong or invalid payload")
+		return fmt.Errorf("e2ap wrapper is unable to set Subscription Delete Failure Sequence Number due to wrong or invalid payload. ErrorCode: %v",size)
 	}
-	newPayload = C.GoBytes(cptr, C.int(size))
 	return
 }