diff --git a/app/controllers/devices_controller.rb b/app/controllers/devices_controller.rb
index 3a47030..2a11f5d 100644
--- a/app/controllers/devices_controller.rb
+++ b/app/controllers/devices_controller.rb
@@ -1,9 +1,15 @@
 class DevicesController < ApplicationController
+  skip_before_filter :verify_authenticity_token
   respond_to :json
 
   def create
-    device = Device.create(device_params)
-    respond_with device, status: :created
+    device = Device.find_or_initialize_by(unique_id: device_params[:unique_id])
+    device.assign_attributes(device_params)
+    if device.save
+      render json: { access_token: device.access_token }, status: :created
+    else
+      render json: { error: device.errors.full_messages }, status: :unprocessable_entity
+    end
   end
 
   private
diff --git a/spec/controllers/devices_controller_spec.rb b/spec/controllers/devices_controller_spec.rb
index a71fef6..a1dd3b5 100644
--- a/spec/controllers/devices_controller_spec.rb
+++ b/spec/controllers/devices_controller_spec.rb
@@ -4,10 +4,27 @@ RSpec.describe DevicesController, type: :controller do
 
   describe "POST #create" do
     it "creates a device" do
-      expect {
+      expect do
         post :create, device: attributes_for(:device), format: :json
-      }.to change{ Device.count }.by(1)
-      #expect(response).to have_http_status(:success)
+      end.to change{ Device.count }.by(1)
+    end
+
+    describe "when device with existing unique id comes" do
+      before(:example) do
+        device = create(:device)
+        @device_params = { model: "New Device", unique_id: device.unique_id }
+      end
+
+      it "does not create a new device" do
+        expect do
+          post :create, device: @device_params, format: :json
+        end.to change { Device.count }.by(0)
+      end
+
+      it "updated the existing device with new params" do
+        post :create, device: @device_params, format: :json
+        expect(Device.last.model).to eq("New Device")
+      end
     end
   end
 
diff --git a/spec/models/device_spec.rb b/spec/models/device_spec.rb
index 0ac9995..a063287 100644
--- a/spec/models/device_spec.rb
+++ b/spec/models/device_spec.rb
@@ -7,7 +7,7 @@ RSpec.describe Device, type: :model do
   it { should validate_presence_of :model }
   it { should validate_uniqueness_of :unique_id }
 
-  describe "after create" do
+  describe "before create" do
     it "generates an access token for the device" do
       expect(device.access_token).not_to be_nil
     end