diff --git a/app/helpers/user_helper.rb b/app/helpers/user_helper.rb
index 13eab0d14..397fbed7e 100644
--- a/app/helpers/user_helper.rb
+++ b/app/helpers/user_helper.rb
@@ -91,7 +91,7 @@ module UserHelper
   end
 
   def user_action_text(user, attribute)
-    return "Change" if %w[role phone].include?(attribute) && user.send(attribute).present?
+    return "Change" if attribute == "phone_extension" || (%w[role phone].include?(attribute) && user.send(attribute).present?)
 
     ""
   end
diff --git a/app/models/user.rb b/app/models/user.rb
index 92fd37dc8..31d503b86 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -334,12 +334,6 @@ class User < ApplicationRecord
     save!(validate: false)
   end
 
-  def phone_with_extension
-    return phone if phone_extension.blank?
-
-    "#{phone}, Ext. #{phone_extension}"
-  end
-
   def assigned_to_lettings_logs
     lettings_logs.where(assigned_to: self)
   end
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/services/exports/user_export_constants.rb b/app/services/exports/user_export_constants.rb
index 9ce5840d9..15fa10ea0 100644
--- a/app/services/exports/user_export_constants.rb
+++ b/app/services/exports/user_export_constants.rb
@@ -6,6 +6,7 @@ module Exports::UserExportConstants
     "email",
     "name",
     "phone",
+    "extension_number",
     "organisation_id",
     "organisation_name",
     "role",
diff --git a/app/services/exports/user_export_service.rb b/app/services/exports/user_export_service.rb
index 0a8ebe34e..3a9f37417 100644
--- a/app/services/exports/user_export_service.rb
+++ b/app/services/exports/user_export_service.rb
@@ -64,7 +64,8 @@ module Exports
       attribute_hash["role"] = user.role
       attribute_hash["organisation_name"] = user.organisation.name
       attribute_hash["active"] = user.active?
-      attribute_hash["phone"] = [user.phone, user.phone_extension].compact.join(" ")
+      attribute_hash["phone"] = user.phone
+      attribute_hash["extension_number"] = user.phone_extension
       attribute_hash["last_sign_in_at"] = user.last_sign_in_at&.iso8601
       attribute_hash
     end
diff --git a/app/views/users/show.html.erb b/app/views/users/show.html.erb
index a1f104b10..d2ad8b182 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?
+              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 { "••••••••" }
diff --git a/spec/fixtures/exports/user.xml b/spec/fixtures/exports/user.xml
index 4c5286c68..1972e2a9d 100644
--- a/spec/fixtures/exports/user.xml
+++ b/spec/fixtures/exports/user.xml
@@ -8,7 +8,8 @@
     <sign_in_count>5</sign_in_count>
     <last_sign_in_at>2022-03-03T00:00:00+00:00</last_sign_in_at>
     <role>data_provider</role>
-    <phone>1234512345123 123</phone>
+    <phone>1234512345123</phone>
+    <extension_number>123</extension_number>
     <is_dpo>false</is_dpo>
     <is_key_contact>false</is_key_contact>
     <active>true</active>