diff --git a/app/controllers/merge_requests_controller.rb b/app/controllers/merge_requests_controller.rb
index 008738944..c08ce099e 100644
--- a/app/controllers/merge_requests_controller.rb
+++ b/app/controllers/merge_requests_controller.rb
@@ -155,6 +155,8 @@ private
       end
     when "new_organisation_name"
       @merge_request.errors.add(:new_organisation_name, :blank) if merge_request_params[:new_organisation_name].blank?
+    when "new_organisation_telephone_number"
+      @merge_request.errors.add(:new_organisation_telephone_number, :blank) if merge_request_params[:new_organisation_telephone_number].blank?
     end
   end
 
diff --git a/config/locales/en.yml b/config/locales/en.yml
index 0e2500dce..c323a257e 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -135,7 +135,8 @@ en:
             new_organisation_name:
               blank: "Enter an organisation name"
               invalid: "An organisation with this name already exists"
-
+            new_organisation_telephone_number:
+              blank: "Enter a valid telephone number"
 
 
   validations:
diff --git a/spec/requests/merge_requests_controller_spec.rb b/spec/requests/merge_requests_controller_spec.rb
index 5d1add64a..d76cf07e0 100644
--- a/spec/requests/merge_requests_controller_spec.rb
+++ b/spec/requests/merge_requests_controller_spec.rb
@@ -687,33 +687,10 @@ RSpec.describe MergeRequestsController, type: :request do
 
           it "renders the error" do
             request
-            expect(page).to have_content("Enter a telephone number")
-          end
-
-          it "does not update the organisation name" do
-            expect { request }.not_to(change { merge_request.reload.attributes })
-          end
-        end
-
-        context "when the new organisation telephone number already exists" do
-          before do
-            create(:organisation, phone: "1234")
-          end
-
-          let(:params) do
-            { merge_request: { new_organisation_telephone_number: "1234", page: "new_organisation_telephone_number" } }
-          end
-
-          let(:request) do
-            patch "/merge-request/#{merge_request.id}", headers:, params:
-          end
-
-          it "renders the error" do
-            request
-            expect(page).to have_content("An organisation with this telephone number already exists")
+            expect(page).to have_content("Enter a valid telephone number")
           end
 
-          it "does not update the organisation name" do
+          it "does not update the organisation telephone number" do
             expect { request }.not_to(change { merge_request.reload.attributes })
           end
         end