diff --git a/lib/twilio-ruby/rest/messaging/v1/tollfree_verification.rb b/lib/twilio-ruby/rest/messaging/v1/tollfree_verification.rb
index 56ab74ce7..fcc30fb51 100644
--- a/lib/twilio-ruby/rest/messaging/v1/tollfree_verification.rb
+++ b/lib/twilio-ruby/rest/messaging/v1/tollfree_verification.rb
@@ -86,10 +86,10 @@ def create(
                             'BusinessName' => business_name,
                             'BusinessWebsite' => business_website,
                             'NotificationEmail' => notification_email,
-                            'UseCaseCategories' => Twilio.serialize_list(use_case_categories) { |e| e },
+                            'UseCaseCategories' => use_case_categories.is_a?(Array) ? use_case_categories.join(',') : use_case_categories,
                             'UseCaseSummary' => use_case_summary,
                             'ProductionMessageSample' => production_message_sample,
-                            'OptInImageUrls' => Twilio.serialize_list(opt_in_image_urls) { |e| e },
+                            'OptInImageUrls' => opt_in_image_urls.is_a?(Array) ? opt_in_image_urls.join(',') : opt_in_image_urls,
                             'OptInType' => opt_in_type,
                             'MessageVolume' => message_volume,
                             'TollfreePhoneNumberSid' => tollfree_phone_number_sid,
@@ -340,10 +340,10 @@ def update(
                             'BusinessName' => business_name,
                             'BusinessWebsite' => business_website,
                             'NotificationEmail' => notification_email,
-                            'UseCaseCategories' => Twilio.serialize_list(use_case_categories) { |e| e },
+                            'UseCaseCategories' => use_case_categories.is_a?(Array) ? use_case_categories.join(',') : use_case_categories,
                             'UseCaseSummary' => use_case_summary,
                             'ProductionMessageSample' => production_message_sample,
-                            'OptInImageUrls' => Twilio.serialize_list(opt_in_image_urls) { |e| e },
+                            'OptInImageUrls' => opt_in_image_urls.is_a?(Array) ? opt_in_image_urls.join(',') : opt_in_image_urls,
                             'OptInType' => opt_in_type,
                             'MessageVolume' => message_volume,
                             'BusinessStreetAddress' => business_street_address,
diff --git a/spec/rest/messaging/v1/tollfree_verification_spec.rb b/spec/rest/messaging/v1/tollfree_verification_spec.rb
new file mode 100644
index 000000000..685f02095
--- /dev/null
+++ b/spec/rest/messaging/v1/tollfree_verification_spec.rb
@@ -0,0 +1,111 @@
+require 'spec_helper'
+
+describe Twilio::REST::Messaging::V1::TollfreeVerificationList do
+  before do
+    @version = double('version')
+    @tollfree_verification_list = Twilio::REST::Messaging::V1::TollfreeVerificationList.new(@version)
+  end
+
+  describe 'create' do
+    it 'should serialize array parameters as comma-separated strings' do
+      # Mock the version.create method to capture the data sent
+      expect(@version).to receive(:create) do |method, uri, data:, headers:|
+        # Verify that array parameters are serialized as comma-separated strings
+        expect(data['UseCaseCategories']).to eq('ACCOUNT_NOTIFICATIONS,EVENTS')
+        expect(data['OptInImageUrls']).to eq('url1,url2,url3')
+        
+        # Verify other parameters are unchanged
+        expect(data['BusinessName']).to eq('Test Business')
+        expect(data['NotificationEmail']).to eq('test@test.com')
+        
+        # Return a mock payload
+        {
+          'sid' => 'test_sid',
+          'account_sid' => 'test_account_sid',
+          'business_name' => 'Test Business'
+        }
+      end
+
+      result = @tollfree_verification_list.create(
+        business_name: 'Test Business',
+        business_website: 'https://test.com',
+        notification_email: 'test@test.com',
+        use_case_categories: ['ACCOUNT_NOTIFICATIONS', 'EVENTS'],
+        use_case_summary: 'Test summary',
+        production_message_sample: 'Test message',
+        opt_in_image_urls: ['url1', 'url2', 'url3'],
+        opt_in_type: 'WEB_FORM',
+        message_volume: '1,000',
+        tollfree_phone_number_sid: 'test_phone_sid'
+      )
+
+      expect(result).to be_a(Twilio::REST::Messaging::V1::TollfreeVerificationInstance)
+    end
+
+    it 'should handle non-array parameters without modification' do
+      expect(@version).to receive(:create) do |method, uri, data:, headers:|
+        # Verify that non-array parameters pass through unchanged
+        expect(data['UseCaseCategories']).to eq('SINGLE_CATEGORY')
+        expect(data['OptInImageUrls']).to eq('single_url')
+        
+        # Return a mock payload
+        {
+          'sid' => 'test_sid',
+          'account_sid' => 'test_account_sid'
+        }
+      end
+
+      @tollfree_verification_list.create(
+        business_name: 'Test Business',
+        notification_email: 'test@test.com',
+        use_case_categories: 'SINGLE_CATEGORY',
+        opt_in_image_urls: 'single_url',
+        tollfree_phone_number_sid: 'test_phone_sid'
+      )
+    end
+
+    it 'should handle empty arrays correctly' do
+      expect(@version).to receive(:create) do |method, uri, data:, headers:|
+        # Verify that empty arrays become empty strings
+        expect(data['UseCaseCategories']).to eq('')
+        expect(data['OptInImageUrls']).to eq('')
+        
+        # Return a mock payload
+        {
+          'sid' => 'test_sid',
+          'account_sid' => 'test_account_sid'
+        }
+      end
+
+      @tollfree_verification_list.create(
+        business_name: 'Test Business',
+        notification_email: 'test@test.com',
+        use_case_categories: [],
+        opt_in_image_urls: [],
+        tollfree_phone_number_sid: 'test_phone_sid'
+      )
+    end
+
+    it 'should handle nil and :unset values correctly' do
+      expect(@version).to receive(:create) do |method, uri, data:, headers:|
+        # Verify that nil and :unset values pass through unchanged
+        expect(data['UseCaseCategories']).to be_nil
+        expect(data['OptInImageUrls']).to eq(:unset)
+        
+        # Return a mock payload
+        {
+          'sid' => 'test_sid',
+          'account_sid' => 'test_account_sid'
+        }
+      end
+
+      @tollfree_verification_list.create(
+        business_name: 'Test Business',
+        notification_email: 'test@test.com',
+        use_case_categories: nil,
+        opt_in_image_urls: :unset,
+        tollfree_phone_number_sid: 'test_phone_sid'
+      )
+    end
+  end
+end
\ No newline at end of file