diff --git a/app/helpers/spree/quad_pay_helper.rb b/app/helpers/spree/quad_pay_helper.rb
index f2e2dce..1e02aec 100644
--- a/app/helpers/spree/quad_pay_helper.rb
+++ b/app/helpers/spree/quad_pay_helper.rb
@@ -2,8 +2,10 @@ module Spree
   module QuadPayHelper
     QUADPAY_WIDGET_URL_BASE = "https://widgets.quadpay.com"
 
+    # NOTE: customize line 8 for Spree 3.0.0-stable
+    # Spree::BillingIntegration::QuadPayCheckout.available_on_front_end.exists?(active: true)
     def quadpay_active_on_front_end?
-      Spree::BillingIntegration::QuadPayCheckout.available_on_front_end.exists?(active: true)
+      Spree::BillingIntegration::QuadPayCheckout.exists?(active: true)
     end
 
     def display_quadpay_widget_on_product_page?
diff --git a/app/models/spree/billing_integration/quad_pay_checkout.rb b/app/models/spree/billing_integration/quad_pay_checkout.rb
index ef25a4f..80e7137 100644
--- a/app/models/spree/billing_integration/quad_pay_checkout.rb
+++ b/app/models/spree/billing_integration/quad_pay_checkout.rb
@@ -83,6 +83,9 @@ def auto_capture?
     true
   end
 
+  # NOTE: Add phone to params via order.phone field.
+  # Add Callback url. See line
+  # See line 97.
   def build_order_params(order)
     billing_address = order.billing_address
     shipping_address = order.shipping_address
@@ -91,7 +94,7 @@ def build_order_params(order)
       'description': "Order ##{order.number}",
       'amount': number_to_currency(order.total.to_f, unit: ''),
       'consumer': {
-        'phoneNumber': billing_address.phone,
+        'phoneNumber': order.phone,
         'givenNames': billing_address.first_name,
         'surname': billing_address.last_name,
         'email': order.email
@@ -113,7 +116,8 @@ def build_order_params(order)
       'items': line_item_as_json(order),
       'merchant': {
         'redirectConfirmUrl': "#{site_url}/orders/quadpay_confirm",
-        'redirectCancelUrl': "#{site_url}/orders/quadpay_cancel"
+        'redirectCancelUrl': "#{site_url}/orders/quadpay_cancel",
+        'statusCallbackUrl': "#{site_url}/orders/quadpay_callback"
       },
       'merchantReference': order.number,
       'taxAmount': number_to_currency(order.tax_total, unit: ''),
diff --git a/app/models/spree/order_decorator.rb b/app/models/spree/order_decorator.rb
index 354dd5c..4377e49 100644
--- a/app/models/spree/order_decorator.rb
+++ b/app/models/spree/order_decorator.rb
@@ -1,11 +1,13 @@
 Spree::Order.class_eval do
   def available_payment_methods
-    qpm_ids = Spree::BillingIntegration::QuadPayCheckout.active.ids
-    @available_payment_methods ||= 
+    # NOTE: Customize for Spree 3.0.0
+    # See lines 5,6,8,10
+    qpm_ids = Spree::BillingIntegration::QuadPayCheckout.where(active: true).ids
+    @available_payment_methods ||=
       if qpm_ids.any? && (self.total < Spree::Config.quad_pay_min_amount.to_f || self.total > Spree::Config.quad_pay_max_amount.to_f)
-        Spree::PaymentMethod.available_on_front_end.where.not(id: qpm_ids)
+        Spree::PaymentMethod.where(active: true).where.not(id: qpm_ids)
       else
-        Spree::PaymentMethod.available_on_front_end
+        Spree::PaymentMethod.where(active: true)
       end
   end
 end
diff --git a/config/routes.rb b/config/routes.rb
index 732f88f..dca4e98 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -6,8 +6,9 @@
       get :quadpay_confirm
     end
   end
-
-  namespace :admin, path: Spree.admin_path do
+  # NOTE: Make routes working for our project
+  # Removed path parameter for namespace below.
+  namespace :admin do
     resources :quad_pay_settings, :only => [] do
       collection do
         get :edit
diff --git a/lib/active_merchant/billing/quad_pay_api.rb b/lib/active_merchant/billing/quad_pay_api.rb
index a9761c3..4795a23 100644
--- a/lib/active_merchant/billing/quad_pay_api.rb
+++ b/lib/active_merchant/billing/quad_pay_api.rb
@@ -22,6 +22,8 @@ def auth_end_point
           end
       end
 
+      # NOTE: Fixed depreceted base url for test mode.
+      # See line 30
       def auth_audience
         @auth_audience ||=
           if @test_mode
@@ -34,7 +36,7 @@ def auth_audience
       def base_url
         @base_url ||=
           if @test_mode
-            'https://api-ci.quadpay.com'
+            'https://api-ut.quadpay.com'
           else
             'https://api.quadpay.com'
           end
diff --git a/lib/tasks/quad_pay_tasks.rake b/lib/tasks/quad_pay_tasks.rake
index 7381755..471d05b 100644
--- a/lib/tasks/quad_pay_tasks.rake
+++ b/lib/tasks/quad_pay_tasks.rake
@@ -1,6 +1,9 @@
+# NOTE: Customization for Spree 3.0.0
+# Stop using available_on_frontend method, using just where(active: true)
+# See line 5
 namespace :quad_pay_tasks do
   task sync_orders: :environment do
-    qpms = Spree::BillingIntegration::QuadPayCheckout.available_on_front_end.active
+    qpms = Spree::BillingIntegration::QuadPayCheckout.where(active: true)
     if qpm = qpms.first
       quad_pay_payments = quad_pay_payments(qpms)
       quad_pay_payments.each do |payment|
diff --git a/spree_quad_pay.gemspec b/spree_quad_pay.gemspec
index db5c2be..d4e10e4 100644
--- a/spree_quad_pay.gemspec
+++ b/spree_quad_pay.gemspec
@@ -16,7 +16,7 @@ Gem::Specification.new do |s|
   s.require_path = 'lib'
   s.requirements << 'none'
 
-  spree_version = '>= 3.2.0', '< 4.0'
+  spree_version = '>= 3.0.0', '< 4.0'
   s.add_dependency 'spree_core', spree_version
 
   s.add_development_dependency 'capybara', '~> 2.6'