diff --git a/config/locales/en.yml b/config/locales/en.yml
index c225392a4..c8876754a 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -114,6 +114,12 @@ en:
       reauthorization:
         generic: 'Failed to reauthorize WhatsApp. Please try again.'
         not_supported: 'Reauthorization is not supported for this type of WhatsApp channel.'
+      calls:
+        not_enabled: 'Calling is not enabled for this inbox'
+        no_recording: 'No recording file provided'
+        no_message: 'Call has no associated message'
+        sdp_offer_required: 'sdp_offer is required'
+        permission_request_failed: 'Failed to send call permission request'
     inboxes:
       imap:
         socket_error: Please check the network connection, IMAP address and try again.
diff --git a/enterprise/app/controllers/api/v1/accounts/whatsapp_calls_controller.rb b/enterprise/app/controllers/api/v1/accounts/whatsapp_calls_controller.rb
index 801e2d392..7ab777be5 100644
--- a/enterprise/app/controllers/api/v1/accounts/whatsapp_calls_controller.rb
+++ b/enterprise/app/controllers/api/v1/accounts/whatsapp_calls_controller.rb
@@ -20,29 +20,34 @@ class Api::V1::Accounts::WhatsappCallsController < Api::V1::Accounts::BaseContro
     @call = Whatsapp::CallService.new(call: @call, agent: Current.user).terminate
   end
 
-  # Browser-supplied recording captured via MediaRecorder during the call.
-  # Idempotent: subsequent uploads no-op once the first audio attachment exists.
+  # Browser-supplied recording captured via MediaRecorder. Idempotent: the
+  # check-and-create runs under the message row lock so the hangup-vs-pagehide
+  # race can't double-attach.
   def upload_recording
-    return render_could_not_create_error('No recording file provided') if params[:recording].blank?
-    return render_could_not_create_error('Call has no associated message') if @call.message.blank?
+    return render_could_not_create_error(I18n.t('errors.whatsapp.calls.no_recording')) if params[:recording].blank?
+    return render_could_not_create_error(I18n.t('errors.whatsapp.calls.no_message')) if @call.message.blank?
 
-    @upload_status = if @call.message.attachments.exists?(file_type: :audio)
-                       'already_uploaded'
-                     else
-                       @call.message.attachments.create!(account_id: @call.account_id, file_type: :audio, file: params[:recording])
-                       'uploaded'
-                     end
+    @call.message.with_lock do
+      @upload_status = if @call.message.attachments.exists?(file_type: :audio)
+                         'already_uploaded'
+                       else
+                         @call.message.attachments.create!(account_id: @call.account_id, file_type: :audio, file: params[:recording])
+                         'uploaded'
+                       end
+    end
   end
 
   def initiate
-    return render_could_not_create_error('Calling is not enabled for this inbox') unless calling_enabled?(@conversation)
-    return render_could_not_create_error('sdp_offer is required') if params[:sdp_offer].blank?
+    return render_could_not_create_error(I18n.t('errors.whatsapp.calls.not_enabled')) unless calling_enabled?(@conversation)
+    return render_could_not_create_error(I18n.t('errors.whatsapp.calls.sdp_offer_required')) if params[:sdp_offer].blank?
 
     @call = create_outbound_call(@conversation, params[:sdp_offer])
     @message = Voice::CallMessageBuilder.new(@call).perform!
     @call.update!(message_id: @message.id)
   rescue Voice::CallErrors::NoCallPermission
     handle_no_call_permission(@conversation)
+  rescue Voice::CallErrors::CallFailed => e
+    render_could_not_create_error(e.message)
   end
 
   private
@@ -87,7 +92,7 @@ class Api::V1::Accounts::WhatsappCallsController < Api::V1::Accounts::BaseContro
 
     contact_phone = conversation.contact.phone_number.delete('+')
     sent = conversation.inbox.channel.provider_service.send_call_permission_request(contact_phone)
-    return render_could_not_create_error('Failed to send call permission request') unless sent
+    return render_could_not_create_error(I18n.t('errors.whatsapp.calls.permission_request_failed')) unless sent
 
     attrs = (conversation.additional_attributes || {}).merge('call_permission_requested_at' => Time.current.iso8601)
     conversation.update!(additional_attributes: attrs)
diff --git a/enterprise/app/services/whatsapp/call_service.rb b/enterprise/app/services/whatsapp/call_service.rb
index 5802b379e..f734f332e 100644
--- a/enterprise/app/services/whatsapp/call_service.rb
+++ b/enterprise/app/services/whatsapp/call_service.rb
@@ -12,19 +12,24 @@ class Whatsapp::CallService
   end
 
   def reject
-    call.reload
-    return call if call.terminal? || call.in_progress?
+    call.with_lock do
+      next if call.terminal? || call.in_progress?
 
-    invoke_provider(:reject_call)
-    finalize_call('failed')
+      invoke_provider(:reject_call)
+      finalize_call('failed')
+    end
     call
   end
 
   def terminate
-    return call if call.terminal?
+    call.with_lock do
+      next if call.terminal?
 
-    invoke_provider(:terminate_call)
-    finalize_call('completed')
+      invoke_provider(:terminate_call)
+      # An agent who hangs up before the contact picks up should mark the call no_answer,
+      # mirroring the webhook terminate path in Whatsapp::IncomingCallService.
+      finalize_call(call.in_progress? ? 'completed' : 'no_answer')
+    end
     call
   end
 
diff --git a/spec/enterprise/controllers/api/v1/accounts/whatsapp_calls_controller_spec.rb b/spec/enterprise/controllers/api/v1/accounts/whatsapp_calls_controller_spec.rb
index 857c678bf..40ce454dc 100644
--- a/spec/enterprise/controllers/api/v1/accounts/whatsapp_calls_controller_spec.rb
+++ b/spec/enterprise/controllers/api/v1/accounts/whatsapp_calls_controller_spec.rb
@@ -123,6 +123,17 @@ RSpec.describe 'WhatsApp Calls API', type: :request do
 
       expect(response).to have_http_status(:unprocessable_entity)
     end
+
+    it 'returns 422 when Meta raises CallFailed for non-permission errors' do
+      allow(provider_service).to receive(:initiate_call).and_raise(Voice::CallErrors::CallFailed, 'Meta error')
+
+      post "/api/v1/accounts/#{account.id}/whatsapp_calls/initiate",
+           params: { conversation_id: initiate_conversation.display_id, sdp_offer: 'sdp_offer' },
+           headers: agent.create_new_auth_token
+
+      expect(response).to have_http_status(:unprocessable_entity)
+      expect(response.parsed_body['error']).to eq('Meta error')
+    end
   end
 
   describe 'POST /api/v1/accounts/:account_id/whatsapp_calls/:id/upload_recording' do
diff --git a/spec/enterprise/services/whatsapp/call_service_spec.rb b/spec/enterprise/services/whatsapp/call_service_spec.rb
index 615f2cf03..76752789e 100644
--- a/spec/enterprise/services/whatsapp/call_service_spec.rb
+++ b/spec/enterprise/services/whatsapp/call_service_spec.rb
@@ -88,7 +88,7 @@ describe Whatsapp::CallService do
   describe '#terminate' do
     before { allow(provider_service).to receive(:terminate_call).and_return(true) }
 
-    it 'tells Meta to terminate and finalizes the call as completed' do
+    it 'finalizes an in-progress call as completed' do
       call.update!(status: 'in_progress')
 
       described_class.new(call: call, agent: agent).terminate
@@ -100,5 +100,11 @@ describe Whatsapp::CallService do
         "account_#{account.id}", hash_including(event: 'voice_call.ended')
       )
     end
+
+    it 'finalizes a still-ringing call as no_answer when the agent hangs up before the contact picks up' do
+      described_class.new(call: call, agent: agent).terminate
+
+      expect(call.reload.status).to eq('no_answer')
+    end
   end
 end