diff --git a/app/services/twilio/incoming_message_service.rb b/app/services/twilio/incoming_message_service.rb
index 7a74488e2..026a2fc49 100644
--- a/app/services/twilio/incoming_message_service.rb
+++ b/app/services/twilio/incoming_message_service.rb
@@ -44,6 +44,13 @@ class Twilio::IncomingMessageService
     twilio_channel.sms? ? params[:From] : params[:From].gsub('whatsapp:', '')
   end
 
+  def normalized_phone_number
+    return phone_number unless twilio_channel.whatsapp?
+
+    # Use the generic normalization service for Twilio WhatsApp
+    Whatsapp::PhoneNumberNormalizationService.new(inbox).normalize_and_find_contact_by_provider("whatsapp:#{phone_number}", :twilio)
+  end
+
   def formatted_phone_number
     TelephoneNumber.parse(phone_number).international_number
   end
@@ -53,8 +60,10 @@ class Twilio::IncomingMessageService
   end
 
   def set_contact
+    source_id = twilio_channel.whatsapp? ? normalized_phone_number : params[:From]
+
     contact_inbox = ::ContactInboxWithContactBuilder.new(
-      source_id: params[:From],
+      source_id: source_id,
       inbox: inbox,
       contact_attributes: contact_attributes
     ).perform
diff --git a/app/services/whatsapp/incoming_message_service_helpers.rb b/app/services/whatsapp/incoming_message_service_helpers.rb
index e40dc408f..46ad255aa 100644
--- a/app/services/whatsapp/incoming_message_service_helpers.rb
+++ b/app/services/whatsapp/incoming_message_service_helpers.rb
@@ -48,7 +48,7 @@ module Whatsapp::IncomingMessageServiceHelpers
   end
 
   def processed_waid(waid)
-    Whatsapp::PhoneNumberNormalizationService.new(inbox).normalize_and_find_contact(waid)
+    Whatsapp::PhoneNumberNormalizationService.new(inbox).normalize_and_find_contact_by_provider(waid, :cloud)
   end
 
   def error_webhook_event?(message)
diff --git a/app/services/whatsapp/phone_normalizers/argentina_phone_normalizer.rb b/app/services/whatsapp/phone_normalizers/argentina_phone_normalizer.rb
new file mode 100644
index 000000000..d854ba6f7
--- /dev/null
+++ b/app/services/whatsapp/phone_normalizers/argentina_phone_normalizer.rb
@@ -0,0 +1,13 @@
+class Whatsapp::PhoneNormalizers::ArgentinaPhoneNormalizer < Whatsapp::PhoneNormalizers::BasePhoneNormalizer
+  def handles_country?(waid)
+    waid.start_with?('549')
+  end
+
+  def normalize(waid)
+    return waid unless handles_country?(waid)
+
+    # Remove the '9' after country code for Argentina numbers
+    # 5491123456789 -> 541123456789
+    waid.sub(/^549/, '54')
+  end
+end
diff --git a/app/services/whatsapp/phone_number_normalization_service.rb b/app/services/whatsapp/phone_number_normalization_service.rb
index b8e416794..76421e899 100644
--- a/app/services/whatsapp/phone_number_normalization_service.rb
+++ b/app/services/whatsapp/phone_number_normalization_service.rb
@@ -1,23 +1,40 @@
 # Service to handle phone number normalization for WhatsApp messages
-# Currently supports Brazil phone number format variations
+# Currently supports Brazil and Argentina phone number format variations
+# Supports both WhatsApp Cloud API and Twilio WhatsApp providers
 # Designed to be extensible for additional countries in future PRs
 #
-# Usage: Whatsapp::PhoneNumberNormalizationService.new(inbox).normalize_and_find_contact(waid)
+# Usage:
+#   Whatsapp::PhoneNumberNormalizationService.new(inbox).normalize_and_find_contact_by_provider(number, :cloud)
+#   Whatsapp::PhoneNumberNormalizationService.new(inbox).normalize_and_find_contact_by_provider(number, :twilio)
 class Whatsapp::PhoneNumberNormalizationService
   def initialize(inbox)
     @inbox = inbox
   end
 
-  # Main entry point for phone number normalization
-  # Returns the source_id of an existing contact if found, otherwise returns original waid
-  def normalize_and_find_contact(waid)
-    normalizer = find_normalizer_for_country(waid)
-    return waid unless normalizer
+  # Generic method to handle both WhatsApp Cloud and Twilio formats
+  # Extracts clean number, normalizes it, and returns appropriate format for provider
+  #
+  # @param raw_number [String] The phone number in provider-specific format
+  #   - Cloud: "919745786257" (clean number)
+  #   - Twilio: "whatsapp:+919745786257" (prefixed format)
+  # @param provider [Symbol] :cloud or :twilio
+  # @return [String] Normalized source_id in provider format or original if not found
+  def normalize_and_find_contact_by_provider(raw_number, provider)
+    # Extract clean number based on provider format
+    clean_number = extract_clean_number(raw_number, provider)
 
-    normalized_waid = normalizer.normalize(waid)
-    existing_contact_inbox = find_existing_contact_inbox(normalized_waid)
+    # Find appropriate normalizer for the country
+    normalizer = find_normalizer_for_country(clean_number)
+    return raw_number unless normalizer
 
-    existing_contact_inbox&.source_id || waid
+    # Normalize the clean number
+    normalized_clean_number = normalizer.normalize(clean_number)
+
+    # Format for provider and check for existing contact
+    provider_format = format_for_provider(normalized_clean_number, provider)
+    existing_contact_inbox = find_existing_contact_inbox(provider_format)
+
+    existing_contact_inbox&.source_id || raw_number
   end
 
   private
@@ -33,7 +50,32 @@ class Whatsapp::PhoneNumberNormalizationService
     inbox.contact_inboxes.find_by(source_id: normalized_waid)
   end
 
+  # Extract clean number from provider-specific format
+  def extract_clean_number(raw_number, provider)
+    case provider
+    when :cloud
+      raw_number # Already clean: "919745786257"
+    when :twilio
+      raw_number.gsub(/^whatsapp:\+/, '') # Remove prefix: "whatsapp:+919745786257" → "919745786257"
+    else
+      raise ArgumentError, "Unsupported provider: #{provider}. Use :cloud or :twilio"
+    end
+  end
+
+  # Format normalized number for provider-specific storage
+  def format_for_provider(clean_number, provider)
+    case provider
+    when :cloud
+      clean_number # Keep clean: "919745786257"
+    when :twilio
+      "whatsapp:+#{clean_number}" # Add prefix: "919745786257" → "whatsapp:+919745786257"
+    else
+      raise ArgumentError, "Unsupported provider: #{provider}. Use :cloud or :twilio"
+    end
+  end
+
   NORMALIZERS = [
-    Whatsapp::PhoneNormalizers::BrazilPhoneNormalizer
+    Whatsapp::PhoneNormalizers::BrazilPhoneNormalizer,
+    Whatsapp::PhoneNormalizers::ArgentinaPhoneNormalizer
   ].freeze
 end
diff --git a/spec/factories/channel/twilio_sms.rb b/spec/factories/channel/twilio_sms.rb
index 94f632efd..1963a4f28 100644
--- a/spec/factories/channel/twilio_sms.rb
+++ b/spec/factories/channel/twilio_sms.rb
@@ -13,5 +13,9 @@ FactoryBot.define do
       sequence(:phone_number) { |n| "+123456789#{n}1" }
       messaging_service_sid { nil }
     end
+
+    trait :whatsapp do
+      medium { :whatsapp }
+    end
   end
 end
diff --git a/spec/services/twilio/incoming_message_service_spec.rb b/spec/services/twilio/incoming_message_service_spec.rb
index d32ef59bb..9b9f33445 100644
--- a/spec/services/twilio/incoming_message_service_spec.rb
+++ b/spec/services/twilio/incoming_message_service_spec.rb
@@ -402,6 +402,234 @@ describe Twilio::IncomingMessageService do
         existing_contact.reload
         expect(existing_contact.name).to eq('Alice Johnson')
       end
+
+      context 'when handling Brazilian WhatsApp numbers' do
+        let!(:whatsapp_twilio_channel) do
+          create(:channel_twilio_sms, :whatsapp, account: account, account_sid: 'ACxxx',
+                                                 inbox: create(:inbox, account: account, greeting_enabled: false))
+        end
+
+        describe 'When the incoming number is a Brazilian number in new format with 9 included' do
+          it 'creates appropriate conversations, message and contacts if contact does not exist' do
+            params = {
+              SmsSid: 'SMxx',
+              From: 'whatsapp:+5541988887777',
+              AccountSid: 'ACxxx',
+              MessagingServiceSid: whatsapp_twilio_channel.messaging_service_sid,
+              Body: 'Test message from Brazil',
+              ProfileName: 'João Silva'
+            }
+
+            described_class.new(params: params).perform
+
+            expect(whatsapp_twilio_channel.inbox.conversations.count).not_to eq(0)
+            expect(whatsapp_twilio_channel.inbox.contacts.first.name).to eq('João Silva')
+            expect(whatsapp_twilio_channel.inbox.messages.first.content).to eq('Test message from Brazil')
+            expect(whatsapp_twilio_channel.inbox.contact_inboxes.first.source_id).to eq('whatsapp:+5541988887777')
+          end
+
+          it 'appends to existing contact if contact inbox exists' do
+            # Create existing contact with same format
+            normalized_contact = create(:contact, account: account, phone_number: '+5541988887777')
+            contact_inbox = create(:contact_inbox, source_id: 'whatsapp:+5541988887777', contact: normalized_contact,
+                                                   inbox: whatsapp_twilio_channel.inbox)
+            last_conversation = create(:conversation, inbox: whatsapp_twilio_channel.inbox, contact_inbox: contact_inbox)
+
+            params = {
+              SmsSid: 'SMxx',
+              From: 'whatsapp:+5541988887777',
+              AccountSid: 'ACxxx',
+              MessagingServiceSid: whatsapp_twilio_channel.messaging_service_sid,
+              Body: 'Another message from Brazil',
+              ProfileName: 'João Silva'
+            }
+
+            described_class.new(params: params).perform
+
+            # No new conversation should be created
+            expect(whatsapp_twilio_channel.inbox.conversations.count).to eq(1)
+            # Message appended to the last conversation
+            expect(last_conversation.messages.last.content).to eq('Another message from Brazil')
+          end
+        end
+
+        describe 'When incoming number is a Brazilian number in old format without the 9 included' do
+          context 'when a contact inbox exists in the old format without 9 included' do
+            it 'appends to existing contact' do
+              # Create existing contact with old format (12 digits)
+              old_contact = create(:contact, account: account, phone_number: '+554188887777')
+              contact_inbox = create(:contact_inbox, source_id: 'whatsapp:+554188887777', contact: old_contact, inbox: whatsapp_twilio_channel.inbox)
+              last_conversation = create(:conversation, inbox: whatsapp_twilio_channel.inbox, contact_inbox: contact_inbox)
+
+              params = {
+                SmsSid: 'SMxx',
+                From: 'whatsapp:+554188887777',
+                AccountSid: 'ACxxx',
+                MessagingServiceSid: whatsapp_twilio_channel.messaging_service_sid,
+                Body: 'Test message from Brazil old format',
+                ProfileName: 'Maria Silva'
+              }
+
+              described_class.new(params: params).perform
+
+              # No new conversation should be created
+              expect(whatsapp_twilio_channel.inbox.conversations.count).to eq(1)
+              # Message appended to the last conversation
+              expect(last_conversation.messages.last.content).to eq('Test message from Brazil old format')
+            end
+          end
+
+          context 'when a contact inbox exists in the new format with 9 included' do
+            it 'appends to existing contact' do
+              # Create existing contact with new format (13 digits)
+              normalized_contact = create(:contact, account: account, phone_number: '+5541988887777')
+              contact_inbox = create(:contact_inbox, source_id: 'whatsapp:+5541988887777', contact: normalized_contact,
+                                                     inbox: whatsapp_twilio_channel.inbox)
+              last_conversation = create(:conversation, inbox: whatsapp_twilio_channel.inbox, contact_inbox: contact_inbox)
+
+              # Incoming message with old format (12 digits)
+              params = {
+                SmsSid: 'SMxx',
+                From: 'whatsapp:+554188887777',
+                AccountSid: 'ACxxx',
+                MessagingServiceSid: whatsapp_twilio_channel.messaging_service_sid,
+                Body: 'Test message from Brazil',
+                ProfileName: 'João Silva'
+              }
+
+              described_class.new(params: params).perform
+
+              # Should find and use existing contact, not create duplicate
+              expect(whatsapp_twilio_channel.inbox.conversations.count).to eq(1)
+              # Message appended to the existing conversation
+              expect(last_conversation.messages.last.content).to eq('Test message from Brazil')
+              # Should use the existing contact's source_id (normalized format)
+              expect(whatsapp_twilio_channel.inbox.contact_inboxes.first.source_id).to eq('whatsapp:+5541988887777')
+            end
+          end
+
+          context 'when a contact inbox does not exist in the new format with 9 included' do
+            it 'creates contact inbox with the incoming number' do
+              params = {
+                SmsSid: 'SMxx',
+                From: 'whatsapp:+554188887777',
+                AccountSid: 'ACxxx',
+                MessagingServiceSid: whatsapp_twilio_channel.messaging_service_sid,
+                Body: 'Test message from Brazil',
+                ProfileName: 'Carlos Silva'
+              }
+
+              described_class.new(params: params).perform
+
+              expect(whatsapp_twilio_channel.inbox.conversations.count).not_to eq(0)
+              expect(whatsapp_twilio_channel.inbox.contacts.first.name).to eq('Carlos Silva')
+              expect(whatsapp_twilio_channel.inbox.messages.first.content).to eq('Test message from Brazil')
+              expect(whatsapp_twilio_channel.inbox.contact_inboxes.first.source_id).to eq('whatsapp:+554188887777')
+            end
+          end
+        end
+      end
+
+      context 'when handling Argentine WhatsApp numbers' do
+        let!(:whatsapp_twilio_channel) do
+          create(:channel_twilio_sms, :whatsapp, account: account, account_sid: 'ACxxx',
+                                                 inbox: create(:inbox, account: account, greeting_enabled: false))
+        end
+
+        describe 'When the incoming number is an Argentine number with 9 after country code' do
+          it 'creates appropriate conversations, message and contacts if contact does not exist' do
+            params = {
+              SmsSid: 'SMxx',
+              From: 'whatsapp:+5491123456789',
+              AccountSid: 'ACxxx',
+              MessagingServiceSid: whatsapp_twilio_channel.messaging_service_sid,
+              Body: 'Test message from Argentina',
+              ProfileName: 'Carlos Mendoza'
+            }
+
+            described_class.new(params: params).perform
+
+            expect(whatsapp_twilio_channel.inbox.conversations.count).not_to eq(0)
+            expect(whatsapp_twilio_channel.inbox.contacts.first.name).to eq('Carlos Mendoza')
+            expect(whatsapp_twilio_channel.inbox.messages.first.content).to eq('Test message from Argentina')
+            expect(whatsapp_twilio_channel.inbox.contact_inboxes.first.source_id).to eq('whatsapp:+5491123456789')
+          end
+
+          it 'appends to existing contact if contact inbox exists with normalized format' do
+            # Create existing contact with normalized format (without 9 after country code)
+            normalized_contact = create(:contact, account: account, phone_number: '+541123456789')
+            contact_inbox = create(:contact_inbox, source_id: 'whatsapp:+541123456789', contact: normalized_contact,
+                                                   inbox: whatsapp_twilio_channel.inbox)
+            last_conversation = create(:conversation, inbox: whatsapp_twilio_channel.inbox, contact_inbox: contact_inbox)
+
+            # Incoming message with 9 after country code
+            params = {
+              SmsSid: 'SMxx',
+              From: 'whatsapp:+5491123456789',
+              AccountSid: 'ACxxx',
+              MessagingServiceSid: whatsapp_twilio_channel.messaging_service_sid,
+              Body: 'Test message from Argentina',
+              ProfileName: 'Carlos Mendoza'
+            }
+
+            described_class.new(params: params).perform
+
+            # Should find and use existing contact, not create duplicate
+            expect(whatsapp_twilio_channel.inbox.conversations.count).to eq(1)
+            # Message appended to the existing conversation
+            expect(last_conversation.messages.last.content).to eq('Test message from Argentina')
+            # Should use the normalized source_id from existing contact
+            expect(whatsapp_twilio_channel.inbox.contact_inboxes.first.source_id).to eq('whatsapp:+541123456789')
+          end
+        end
+
+        describe 'When incoming number is an Argentine number without 9 after country code' do
+          context 'when a contact inbox exists with the same format' do
+            it 'appends to existing contact' do
+              # Create existing contact with same format (without 9)
+              contact = create(:contact, account: account, phone_number: '+541123456789')
+              contact_inbox = create(:contact_inbox, source_id: 'whatsapp:+541123456789', contact: contact, inbox: whatsapp_twilio_channel.inbox)
+              last_conversation = create(:conversation, inbox: whatsapp_twilio_channel.inbox, contact_inbox: contact_inbox)
+
+              params = {
+                SmsSid: 'SMxx',
+                From: 'whatsapp:+541123456789',
+                AccountSid: 'ACxxx',
+                MessagingServiceSid: whatsapp_twilio_channel.messaging_service_sid,
+                Body: 'Test message from Argentina',
+                ProfileName: 'Ana García'
+              }
+
+              described_class.new(params: params).perform
+
+              # No new conversation should be created
+              expect(whatsapp_twilio_channel.inbox.conversations.count).to eq(1)
+              # Message appended to the last conversation
+              expect(last_conversation.messages.last.content).to eq('Test message from Argentina')
+            end
+          end
+
+          context 'when a contact inbox does not exist' do
+            it 'creates contact inbox with the incoming number' do
+              params = {
+                SmsSid: 'SMxx',
+                From: 'whatsapp:+541123456789',
+                AccountSid: 'ACxxx',
+                MessagingServiceSid: whatsapp_twilio_channel.messaging_service_sid,
+                Body: 'Test message from Argentina',
+                ProfileName: 'Diego López'
+              }
+
+              described_class.new(params: params).perform
+
+              expect(whatsapp_twilio_channel.inbox.conversations.count).not_to eq(0)
+              expect(whatsapp_twilio_channel.inbox.contacts.first.name).to eq('Diego López')
+              expect(whatsapp_twilio_channel.inbox.messages.first.content).to eq('Test message from Argentina')
+              expect(whatsapp_twilio_channel.inbox.contact_inboxes.first.source_id).to eq('whatsapp:+541123456789')
+            end
+          end
+        end
+      end
     end
   end
 end
diff --git a/spec/services/whatsapp/phone_number_normalization_service_spec.rb b/spec/services/whatsapp/phone_number_normalization_service_spec.rb
new file mode 100644
index 000000000..bd89c8916
--- /dev/null
+++ b/spec/services/whatsapp/phone_number_normalization_service_spec.rb
@@ -0,0 +1,95 @@
+require 'rails_helper'
+
+RSpec.describe Whatsapp::PhoneNumberNormalizationService do
+  let(:account) { create(:account) }
+  let(:inbox) { create(:inbox, account: account) }
+  let(:service) { described_class.new(inbox) }
+
+  describe '#normalize_and_find_contact_by_provider' do
+    context 'when handling Brazilian numbers' do
+      context 'with WhatsApp Cloud provider' do
+        it 'normalizes old format and finds existing contact with new format' do
+          # Create existing contact with new format (13 digits)
+          create(:contact_inbox, inbox: inbox, source_id: '5541988887777')
+
+          # Incoming old format (12 digits)
+          result = service.normalize_and_find_contact_by_provider('554188887777', :cloud)
+
+          expect(result).to eq('5541988887777')
+        end
+
+        it 'returns original if no existing contact found' do
+          result = service.normalize_and_find_contact_by_provider('554188887777', :cloud)
+
+          expect(result).to eq('554188887777')
+        end
+      end
+
+      context 'with Twilio provider' do
+        it 'normalizes old format and finds existing contact with new format' do
+          # Create existing contact with new format (Twilio format with 13 digits)
+          create(:contact_inbox, inbox: inbox, source_id: 'whatsapp:+5541988887777')
+
+          # Incoming old format (Twilio format with 12 digits)
+          result = service.normalize_and_find_contact_by_provider('whatsapp:+554188887777', :twilio)
+
+          expect(result).to eq('whatsapp:+5541988887777')
+        end
+
+        it 'returns original if no existing contact found' do
+          result = service.normalize_and_find_contact_by_provider('whatsapp:+554188887777', :twilio)
+
+          expect(result).to eq('whatsapp:+554188887777')
+        end
+      end
+    end
+
+    context 'when handling Argentine numbers' do
+      context 'with WhatsApp Cloud provider' do
+        it 'normalizes number with 9 and finds existing contact without 9' do
+          # Create existing contact with normalized format (without 9)
+          create(:contact_inbox, inbox: inbox, source_id: '541123456789')
+
+          # Incoming format with 9 after country code
+          result = service.normalize_and_find_contact_by_provider('5491123456789', :cloud)
+
+          expect(result).to eq('541123456789')
+        end
+      end
+
+      context 'with Twilio provider' do
+        it 'normalizes number with 9 and finds existing contact without 9' do
+          # Create existing contact with normalized format (Twilio format without 9)
+          create(:contact_inbox, inbox: inbox, source_id: 'whatsapp:+541123456789')
+
+          # Incoming format with 9 after country code (Twilio format)
+          result = service.normalize_and_find_contact_by_provider('whatsapp:+5491123456789', :twilio)
+
+          expect(result).to eq('whatsapp:+541123456789')
+        end
+      end
+    end
+
+    context 'when handling unsupported countries' do
+      it 'returns original number for WhatsApp Cloud' do
+        result = service.normalize_and_find_contact_by_provider('919876543210', :cloud)
+
+        expect(result).to eq('919876543210')
+      end
+
+      it 'returns original number for Twilio' do
+        result = service.normalize_and_find_contact_by_provider('whatsapp:+919876543210', :twilio)
+
+        expect(result).to eq('whatsapp:+919876543210')
+      end
+    end
+
+    context 'when handling invalid provider' do
+      it 'raises ArgumentError for unsupported provider' do
+        expect do
+          service.normalize_and_find_contact_by_provider('919876543210', :unknown)
+        end.to raise_error(ArgumentError, 'Unsupported provider: unknown. Use :cloud or :twilio')
+      end
+    end
+  end
+end