diff --git a/app/helpers/user_helper.rb b/app/helpers/user_helper.rb
index 13eab0d14..931f18680 100644
--- a/app/helpers/user_helper.rb
+++ b/app/helpers/user_helper.rb
@@ -85,13 +85,15 @@ module UserHelper
       current_user.data_coordinator? || current_user.support? ? govuk_link_to("Select role", aliased_user_edit(user, current_user), class: "govuk-link govuk-link--no-visited-state") : "No role assigned"
     when "phone"
       govuk_link_to("Enter telephone number", aliased_user_edit(user, current_user), class: "govuk-link govuk-link--no-visited-state")
+    when "phone_extension"
+      current_user.data_coordinator? || current_user.support? ? govuk_link_to("Enter extension number", aliased_user_edit(user, current_user), class: "govuk-link govuk-link--no-visited-state") : "No answer provided"
     else
       "No answer provided"
     end
   end
 
   def user_action_text(user, attribute)
-    return "Change" if %w[role phone].include?(attribute) && user.send(attribute).present?
+    return "Change" if %w[role phone phone_extension].include?(attribute) && user.send(attribute).present?
 
     ""
   end
diff --git a/app/models/user.rb b/app/models/user.rb
index ea8289e53..4e80df2b8 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -335,6 +335,7 @@ class User < ApplicationRecord
   end
 
   def phone_with_extension
+    #use this
     return phone if phone_extension.blank?
 
     "#{phone}, Ext. #{phone_extension}"
diff --git a/app/policies/user_policy.rb b/app/policies/user_policy.rb
index dc8aaf28e..48beb1216 100644
--- a/app/policies/user_policy.rb
+++ b/app/policies/user_policy.rb
@@ -26,6 +26,7 @@ class UserPolicy
   %w[
     edit_emails?
     edit_telephone_numbers?
+    edit_extension_numbers?
     edit_names?
   ].each do |method_name|
     define_method method_name do
diff --git a/app/views/users/show.html.erb b/app/views/users/show.html.erb
index a1f104b10..06fda18a3 100644
--- a/app/views/users/show.html.erb
+++ b/app/views/users/show.html.erb
@@ -65,6 +65,21 @@
             end
           end %>
 
+      <%= summary_list.with_row do |row|
+        row.with_key { "Extension number" }
+        row.with_value { user_details_html(@user, current_user, "phone_extension") }
+        if UserPolicy.new(current_user, @user).edit_extension_numbers? && @user.phone_extension.present?
+          row.with_action(
+            text: user_action_text(@user, "phone_extension"),
+            visually_hidden_text: "extension number",
+            href: aliased_user_edit(@user, current_user),
+            html_attributes: { "data-qa": "change-extension-number" },
+            )
+        else
+          row.with_action
+        end
+      end %>
+
       <%= summary_list.with_row do |row|
             row.with_key { "Password" }
             row.with_value { "••••••••" }