diff --git a/app/services/whatsapp/phone_normalizers/mexico_phone_normalizer.rb b/app/services/whatsapp/phone_normalizers/mexico_phone_normalizer.rb
new file mode 100644
index 000000000..9af5ff385
--- /dev/null
+++ b/app/services/whatsapp/phone_normalizers/mexico_phone_normalizer.rb
@@ -0,0 +1,17 @@
+# Handles Mexico phone number normalization
+#
+# WhatsApp may include a "1" after Mexico's country code (521), while contacts
+# can already be stored without it (52). Normalize to the stored E.164 format.
+class Whatsapp::PhoneNormalizers::MexicoPhoneNormalizer < Whatsapp::PhoneNormalizers::BasePhoneNormalizer
+  def normalize(waid)
+    return waid unless handles_country?(waid)
+
+    waid.sub(/^521/, '52')
+  end
+
+  private
+
+  def country_code_pattern
+    /^52/
+  end
+end
diff --git a/app/services/whatsapp/phone_number_normalization_service.rb b/app/services/whatsapp/phone_number_normalization_service.rb
index 1e52d9b02..853c7d24e 100644
--- a/app/services/whatsapp/phone_number_normalization_service.rb
+++ b/app/services/whatsapp/phone_number_normalization_service.rb
@@ -1,5 +1,5 @@
 # Service to handle phone number normalization for WhatsApp messages
-# Currently supports Brazil and Argentina phone number format variations
+# Currently supports Brazil, Argentina, and Mexico phone number format variations
 # Supports both WhatsApp Cloud API and Twilio WhatsApp providers
 class Whatsapp::PhoneNumberNormalizationService
   def initialize(inbox)
@@ -64,6 +64,7 @@ class Whatsapp::PhoneNumberNormalizationService
 
   NORMALIZERS = [
     Whatsapp::PhoneNormalizers::BrazilPhoneNormalizer,
-    Whatsapp::PhoneNormalizers::ArgentinaPhoneNormalizer
+    Whatsapp::PhoneNormalizers::ArgentinaPhoneNormalizer,
+    Whatsapp::PhoneNormalizers::MexicoPhoneNormalizer
   ].freeze
 end
diff --git a/spec/services/twilio/incoming_message_service_spec.rb b/spec/services/twilio/incoming_message_service_spec.rb
index 190a6c45a..59df55333 100644
--- a/spec/services/twilio/incoming_message_service_spec.rb
+++ b/spec/services/twilio/incoming_message_service_spec.rb
@@ -626,6 +626,57 @@ describe Twilio::IncomingMessageService do
           expect(whatsapp_twilio_channel.inbox.contact_inboxes.first.source_id).to eq('whatsapp:+541123456789')
         end
       end
+
+      describe 'When the incoming number is a Mexican WhatsApp number with 1 after country code' 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
+
+        it 'appends to existing contact when contact inbox exists without the extra 1' do
+          contact = create(:contact, account: account, phone_number: '+525512345678')
+          contact_inbox = create(:contact_inbox,
+                                 source_id: 'whatsapp:+525512345678',
+                                 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:+5215512345678',
+            AccountSid: 'ACxxx',
+            MessagingServiceSid: whatsapp_twilio_channel.messaging_service_sid,
+            Body: 'Test message from Mexico',
+            ProfileName: 'Maria Lopez'
+          }
+
+          described_class.new(params: params).perform
+
+          expect(whatsapp_twilio_channel.inbox.conversations.count).to eq(1)
+          expect(last_conversation.messages.last.content).to eq('Test message from Mexico')
+          expect(whatsapp_twilio_channel.inbox.contact_inboxes.first.source_id)
+            .to eq('whatsapp:+525512345678')
+        end
+
+        it 'creates contact inbox with incoming number when no existing contact matches' do
+          params = {
+            SmsSid: 'SMxx',
+            From: 'whatsapp:+5215512345678',
+            AccountSid: 'ACxxx',
+            MessagingServiceSid: whatsapp_twilio_channel.messaging_service_sid,
+            Body: 'Test message from Mexico',
+            ProfileName: 'Maria Lopez'
+          }
+
+          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('Maria Lopez')
+          expect(whatsapp_twilio_channel.inbox.messages.first.content).to eq('Test message from Mexico')
+          expect(whatsapp_twilio_channel.inbox.contact_inboxes.first.source_id)
+            .to eq('whatsapp:+5215512345678')
+        end
+      end
     end
   end
 end