diff --git a/app/services/whatsapp/incoming_message_base_service.rb b/app/services/whatsapp/incoming_message_base_service.rb
index 00936ff15..09632c5b1 100644
--- a/app/services/whatsapp/incoming_message_base_service.rb
+++ b/app/services/whatsapp/incoming_message_base_service.rb
@@ -113,12 +113,14 @@ class Whatsapp::IncomingMessageBaseService
   end
 
   def set_conversation
+    # Scope reuse to the contact across all its contact_inboxes in this inbox: WhatsApp coexistence
+    # gives one contact multiple source_ids (phone + BSUID), so reopen must not be limited to a single contact_inbox.
+    conversations = @contact.conversations.where(inbox_id: @inbox.id)
     # if lock to single conversation is disabled, we will create a new conversation if previous conversation is resolved
     @conversation = if @inbox.lock_to_single_conversation
-                      @contact_inbox.conversations.last
+                      conversations.last
                     else
-                      @contact_inbox.conversations
-                                    .where.not(status: :resolved).last
+                      conversations.where.not(status: :resolved).last
                     end
     return if @conversation
 
diff --git a/spec/services/whatsapp/incoming_message_service_spec.rb b/spec/services/whatsapp/incoming_message_service_spec.rb
index 430aa1561..01b569cb9 100644
--- a/spec/services/whatsapp/incoming_message_service_spec.rb
+++ b/spec/services/whatsapp/incoming_message_service_spec.rb
@@ -34,8 +34,8 @@ describe Whatsapp::IncomingMessageService do
 
       it 'appends to last conversation when if conversation already exists' do
         contact_inbox = create(:contact_inbox, inbox: whatsapp_channel.inbox, source_id: params[:messages].first[:from])
-        2.times.each { create(:conversation, inbox: whatsapp_channel.inbox, contact_inbox: contact_inbox) }
-        last_conversation = create(:conversation, inbox: whatsapp_channel.inbox, contact_inbox: contact_inbox)
+        2.times.each { create(:conversation, inbox: whatsapp_channel.inbox, contact_inbox: contact_inbox, contact: contact_inbox.contact) }
+        last_conversation = create(:conversation, inbox: whatsapp_channel.inbox, contact_inbox: contact_inbox, contact: contact_inbox.contact)
         described_class.new(inbox: whatsapp_channel.inbox, params: params).perform
         # no new conversation should be created
         expect(whatsapp_channel.inbox.conversations.count).to eq(3)
@@ -46,7 +46,7 @@ describe Whatsapp::IncomingMessageService do
       it 'reopen last conversation if last conversation is resolved and lock to single conversation is enabled' do
         whatsapp_channel.inbox.update(lock_to_single_conversation: true)
         contact_inbox = create(:contact_inbox, inbox: whatsapp_channel.inbox, source_id: params[:messages].first[:from])
-        last_conversation = create(:conversation, inbox: whatsapp_channel.inbox, contact_inbox: contact_inbox)
+        last_conversation = create(:conversation, inbox: whatsapp_channel.inbox, contact_inbox: contact_inbox, contact: contact_inbox.contact)
         last_conversation.update(status: 'resolved')
         described_class.new(inbox: whatsapp_channel.inbox, params: params).perform
         # no new conversation should be created
@@ -59,7 +59,7 @@ describe Whatsapp::IncomingMessageService do
       it 'creates a new conversation if last conversation is resolved and lock to single conversation is disabled' do
         whatsapp_channel.inbox.update(lock_to_single_conversation: false)
         contact_inbox = create(:contact_inbox, inbox: whatsapp_channel.inbox, source_id: params[:messages].first[:from])
-        last_conversation = create(:conversation, inbox: whatsapp_channel.inbox, contact_inbox: contact_inbox)
+        last_conversation = create(:conversation, inbox: whatsapp_channel.inbox, contact_inbox: contact_inbox, contact: contact_inbox.contact)
         last_conversation.update(status: 'resolved')
         described_class.new(inbox: whatsapp_channel.inbox, params: params).perform
         # new conversation should be created
@@ -70,7 +70,7 @@ describe Whatsapp::IncomingMessageService do
       it 'will not create a new conversation if last conversation is not resolved and lock to single conversation is disabled' do
         whatsapp_channel.inbox.update(lock_to_single_conversation: false)
         contact_inbox = create(:contact_inbox, inbox: whatsapp_channel.inbox, source_id: params[:messages].first[:from])
-        last_conversation = create(:conversation, inbox: whatsapp_channel.inbox, contact_inbox: contact_inbox)
+        last_conversation = create(:conversation, inbox: whatsapp_channel.inbox, contact_inbox: contact_inbox, contact: contact_inbox.contact)
         last_conversation.update(status: Conversation.statuses.except('resolved').keys.sample)
         described_class.new(inbox: whatsapp_channel.inbox, params: params).perform
         # new conversation should be created
@@ -238,7 +238,7 @@ describe Whatsapp::IncomingMessageService do
       end
 
       before do
-        create(:conversation, inbox: whatsapp_channel.inbox, contact_inbox: contact_inbox)
+        create(:conversation, inbox: whatsapp_channel.inbox, contact_inbox: contact_inbox, contact: contact_inbox.contact)
         described_class.new(inbox: whatsapp_channel.inbox, params: params).perform
       end
 
@@ -453,7 +453,7 @@ describe Whatsapp::IncomingMessageService do
 
       it 'appends to existing contact if contact inbox exists' do
         contact_inbox = create(:contact_inbox, inbox: whatsapp_channel.inbox, source_id: wa_id)
-        last_conversation = create(:conversation, inbox: whatsapp_channel.inbox, contact_inbox: contact_inbox)
+        last_conversation = create(:conversation, inbox: whatsapp_channel.inbox, contact_inbox: contact_inbox, contact: contact_inbox.contact)
         described_class.new(inbox: whatsapp_channel.inbox, params: params).perform
         # no new conversation should be created
         expect(whatsapp_channel.inbox.conversations.count).to eq(1)
@@ -468,7 +468,7 @@ describe Whatsapp::IncomingMessageService do
       context 'when a contact inbox exists in the old format without 9 included' do
         it 'appends to existing contact' do
           contact_inbox = create(:contact_inbox, inbox: whatsapp_channel.inbox, source_id: wa_id)
-          last_conversation = create(:conversation, inbox: whatsapp_channel.inbox, contact_inbox: contact_inbox)
+          last_conversation = create(:conversation, inbox: whatsapp_channel.inbox, contact_inbox: contact_inbox, contact: contact_inbox.contact)
           described_class.new(inbox: whatsapp_channel.inbox, params: params).perform
           # no new conversation should be created
           expect(whatsapp_channel.inbox.conversations.count).to eq(1)
@@ -480,7 +480,7 @@ describe Whatsapp::IncomingMessageService do
       context 'when a contact inbox exists in the new format with 9 included' do
         it 'appends to existing contact' do
           contact_inbox = create(:contact_inbox, inbox: whatsapp_channel.inbox, source_id: '5541988887777')
-          last_conversation = create(:conversation, inbox: whatsapp_channel.inbox, contact_inbox: contact_inbox)
+          last_conversation = create(:conversation, inbox: whatsapp_channel.inbox, contact_inbox: contact_inbox, contact: contact_inbox.contact)
           described_class.new(inbox: whatsapp_channel.inbox, params: params).perform
           # no new conversation should be created
           expect(whatsapp_channel.inbox.conversations.count).to eq(1)
@@ -515,7 +515,7 @@ describe Whatsapp::IncomingMessageService do
         # Normalized format removes the 9 after country code
         normalized_wa_id = '541123456789'
         contact_inbox = create(:contact_inbox, inbox: whatsapp_channel.inbox, source_id: normalized_wa_id)
-        last_conversation = create(:conversation, inbox: whatsapp_channel.inbox, contact_inbox: contact_inbox)
+        last_conversation = create(:conversation, inbox: whatsapp_channel.inbox, contact_inbox: contact_inbox, contact: contact_inbox.contact)
         described_class.new(inbox: whatsapp_channel.inbox, params: params).perform
         # no new conversation should be created
         expect(whatsapp_channel.inbox.conversations.count).to eq(1)
@@ -532,7 +532,7 @@ describe Whatsapp::IncomingMessageService do
       context 'when a contact inbox exists with the same format' do
         it 'appends to existing contact' do
           contact_inbox = create(:contact_inbox, inbox: whatsapp_channel.inbox, source_id: wa_id)
-          last_conversation = create(:conversation, inbox: whatsapp_channel.inbox, contact_inbox: contact_inbox)
+          last_conversation = create(:conversation, inbox: whatsapp_channel.inbox, contact_inbox: contact_inbox, contact: contact_inbox.contact)
           described_class.new(inbox: whatsapp_channel.inbox, params: params).perform
           # no new conversation should be created
           expect(whatsapp_channel.inbox.conversations.count).to eq(1)