diff --git a/core/grpc_service.go b/core/grpc_service.go
new file mode 100644
index 0000000..a5bc3e5
--- /dev/null
+++ b/core/grpc_service.go
@@ -0,0 +1,154 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+
+ * http://www.apache.org/licenses/LICENSE-2.0
+
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package core
+
+import (
+	"gerrit.opencord.org/voltha-bbsim/device"
+	"gerrit.opencord.org/voltha-bbsim/protos"
+	"github.com/google/gopacket"
+	"github.com/google/gopacket/layers"
+	"golang.org/x/net/context"
+	"google.golang.org/grpc"
+	"log"
+	"net"
+)
+
+// gRPC Service
+func (s *Server) DisableOlt(c context.Context, empty *openolt.Empty) (*openolt.Empty, error) {
+	log.Printf("OLT receives DisableOLT()\n")
+	return new(openolt.Empty), nil
+}
+
+func (s *Server) ReenableOlt(c context.Context, empty *openolt.Empty) (*openolt.Empty, error) {
+	log.Printf("OLT receives Reenable()\n")
+	return new(openolt.Empty), nil
+}
+
+func (s *Server) CollectStatistics(c context.Context, empty *openolt.Empty) (*openolt.Empty, error) {
+	log.Printf("OLT receives CollectStatistics()\n")
+	return new(openolt.Empty), nil
+}
+
+func (s *Server) GetDeviceInfo(c context.Context, empty *openolt.Empty) (*openolt.DeviceInfo, error) {
+	log.Printf("OLT receives GetDeviceInfo()\n")
+	return new(openolt.DeviceInfo), nil
+}
+
+func (s *Server) ActivateOnu(c context.Context, onu *openolt.Onu) (*openolt.Empty, error) {
+	log.Printf("OLT receives ActivateONU()\n")
+	result := device.ValidateONU(*onu, s.Onumap)
+
+	if result == true {
+		matched, error := s.getOnuBySN(onu.SerialNumber)
+		if error != nil {
+			log.Fatalf("%s\n", error)
+		}
+		onuid := onu.OnuId
+		matched.OnuID = onuid
+		matched.InternalState = device.ONU_ACTIVATED
+		log.Printf("ONU IntfID: %d OnuID: %d activated succesufully.\n", onu.IntfId, onu.OnuId)
+	}
+	return new(openolt.Empty), nil
+}
+
+func (s *Server) DeactivateOnu(c context.Context, onu *openolt.Onu) (*openolt.Empty, error) {
+	log.Printf("OLT receives DeactivateONU()\n")
+	return new(openolt.Empty), nil
+}
+
+func (s *Server) DeleteOnu(c context.Context, onu *openolt.Onu) (*openolt.Empty, error) {
+	log.Printf("OLT receives DeleteONU()\n")
+	return new(openolt.Empty), nil
+}
+
+func (s *Server) OmciMsgOut(c context.Context, msg *openolt.OmciMsg) (*openolt.Empty, error) {
+	log.Printf("OLT %d receives OmciMsgOut to IF %v (ONU-ID: %v) pkt:%x.\n", s.Olt.ID, msg.IntfId, msg.OnuId, msg.Pkt)
+	//s.olt.Queue = append(s.olt.Queue, *msg)
+	return new(openolt.Empty), nil
+}
+
+func (s *Server) OnuPacketOut(c context.Context, packet *openolt.OnuPacket) (*openolt.Empty, error) {
+	log.Printf("OLT %d receives OnuPacketOut () to IF-ID:%d ONU-ID %d.\n", s.Olt.ID, packet.IntfId, packet.OnuId)
+	onuid := packet.OnuId
+	intfid := packet.IntfId
+	rawpkt := gopacket.NewPacket(packet.Pkt, layers.LayerTypeEthernet, gopacket.Default)
+	if err := s.onuPacketOut(intfid, onuid, rawpkt); err != nil {
+		return new(openolt.Empty), err
+	}
+	return new(openolt.Empty), nil
+}
+
+func (s *Server) UplinkPacketOut(c context.Context, packet *openolt.UplinkPacket) (*openolt.Empty, error) {
+	log.Printf("OLT %d receives UplinkPacketOut().\n", s.Olt.ID)
+	rawpkt := gopacket.NewPacket(packet.Pkt, layers.LayerTypeEthernet, gopacket.Default)
+	if err := s.uplinkPacketOut(rawpkt); err != nil {
+		return new(openolt.Empty), err
+	}
+	return new(openolt.Empty), nil
+}
+
+func (s *Server) FlowAdd(c context.Context, flow *openolt.Flow) (*openolt.Empty, error) {
+	log.Printf("OLT %d receives FlowAdd().\n", s.Olt.ID)
+	return new(openolt.Empty), nil
+}
+
+func (s *Server) FlowRemove(c context.Context, flow *openolt.Flow) (*openolt.Empty, error) {
+	log.Printf("OLT %d receives FlowRemove().\n", s.Olt.ID)
+	return new(openolt.Empty), nil
+}
+
+func (s *Server) HeartbeatCheck(c context.Context, empty *openolt.Empty) (*openolt.Heartbeat, error) {
+	log.Printf("OLT %d receives HeartbeatCheck().\n", s.Olt.ID)
+	signature := new(openolt.Heartbeat)
+	signature.HeartbeatSignature = s.Olt.HeartbeatSignature
+	return signature, nil
+}
+
+func (s *Server) EnablePonIf(c context.Context, intf *openolt.Interface) (*openolt.Empty, error) {
+	log.Printf("OLT %d receives EnablePonIf().\n", s.Olt.ID)
+	return new(openolt.Empty), nil
+}
+
+func (s *Server) DisablePonIf(c context.Context, intf *openolt.Interface) (*openolt.Empty, error) {
+	log.Printf("OLT %d receives DisablePonIf().\n", s.Olt.ID)
+	return new(openolt.Empty), nil
+}
+
+func (s *Server) Reboot(c context.Context, empty *openolt.Empty) (*openolt.Empty, error) {
+	log.Printf("OLT %d receives Reboot ().\n", s.Olt.ID)
+	return new(openolt.Empty), nil
+}
+
+func (s *Server) EnableIndication(empty *openolt.Empty, stream openolt.Openolt_EnableIndicationServer) error {
+	defer func() {
+		s.gRPCserver.Stop()
+	}()
+	log.Printf("OLT receives EnableInd.\n")
+	if err := s.activateOLT(stream); err != nil {
+		log.Printf("Failed to activate OLT: %v\n", err)
+		return err
+	}
+	log.Println("Core server down.")
+	return nil
+}
+
+func CreateGrpcServer(oltid uint32, npon uint32, nonus uint32, addrport string) (l net.Listener, g *grpc.Server, e error) {
+	log.Printf("Listening %s ...", addrport)
+	g = grpc.NewServer()
+	l, e = net.Listen("tcp", addrport)
+	return
+}