diff --git a/lib/admin_actions/number_change.rb b/lib/admin_actions/number_change.rb
index 13dd810f262809b328c74d8381e6f60cfb9cfb3c..f58ae7f8e449c3d2896a42a07f19d563b23d9111 100644
--- a/lib/admin_actions/number_change.rb
+++ b/lib/admin_actions/number_change.rb
@@ -12,15 +12,11 @@ class AdminAction
 			using FormToH
 
 			def self.for(target_customer, reply:)
-				unless (registration = target_customer.registered?)
-					return EMPromise.reject("Customer not registered")
-				end
-
 				EMPromise.resolve(
 					new(
 						customer_id: target_customer.customer_id,
-						old_backend: target_customer.sgx.strip!.to_s,
-						old_tel: registration.phone
+						old_backend: target_customer.sgx&.strip!&.to_s,
+						old_tel: (reg = target_customer.registered?) ? reg.phone : nil
 					)
 				).then { |x| reply.call(x.form).then(&x.method(:change)) }
 			end
@@ -47,17 +43,22 @@ class AdminAction
 			end
 		end
 
-		NilKey = Struct.new(:key) {
+		class Orphan < StandardError
 			def to_s
-				"Expected a key with a value, but #{key} has no value."
+				"Can't register nil tel to any backend"
+			end
+		end
+
+		class UnknownBackend < StandardError
+			def initialize(backend:, expected:)
+				@backend = backend
+				@expected = expected
 			end
-		}
 
-		UnknownBackend = Struct.new(:backend, :expected) {
 			def to_s
-				"Got unknown backend: #{backend}, expected one of #{expected}"
+				"Got unknown backend: #{@backend}, expected one of #{@expected}"
 			end
-		}
+		end
 
 		def customer_id
 			@attributes[:customer_id]
@@ -84,37 +85,49 @@ class AdminAction
 		end
 
 		def check_forward
-			EMPromise.all([check_noop, check_cat_jid, check_backend])
+			# Without this ordering, it's possible for
+			# check_noop and check_orphan to race,
+			# which creates ambiguity around whether
+			# an actual error will raise or not.
+			check_orphan.then {
+				EMPromise.all([check_noop, check_backend])
+			}
 		end
 
 		def forward
-			repo = TrivialBackendSgxRepo.new(redis: REDIS)
 			EMPromise.all([
-				new_tel != old_tel && change_catapult_fwd!,
-				repo.put(customer_id, new_backend).then { |sgx|
-					sgx.register!(new_tel)
-				},
+				old_tel && new_tel != old_tel && change_catapult_fwd!,
+				update_tel_and_backend,
 				should_disconnect_old_number? && disconnect_bandwidth_number
 			]).then { self }
 		end
 
+		def update_tel_and_backend
+			TrivialBackendSgxRepo.new(redis: REDIS).put(
+				customer_id, new_backend,
+			).then { |sgx| sgx.register!(new_tel) }
+		end
+
+		# If old_tel exists, it's still possible no catapult_fwd has been set.
+		# However, if one exists, we should rename it.
+		# If old_tel does not exist, it's not possible for catapult_fwd
+		# to exist, and it's not possible for there to be value.
+		# to set catapult_fwd to. That's out-of-scope for this command.
 		def change_catapult_fwd!
 			REDIS.rename("catapult_fwd-#{old_tel}", "catapult_fwd-#{new_tel}")
 		end
 
 		def to_reverse
 			with(
-				old_tel: new_tel,
-				new_tel: old_tel,
-				old_backend: new_backend,
-				new_backend: old_backend
+				old_tel: new_tel, new_tel: old_tel,
+				old_backend: new_backend, new_backend: old_backend
 			)
 		end
 
 		def to_s
 			base = "Change Number\n"
 			base += "	[move backend?]: #{old_backend} -> #{new_backend}\n"
-			base += "	[change number?]: #{old_tel} -> #{new_tel}"
+			base += "	[change number?]: #{old_tel || 'nil'} -> #{new_tel}"
 			base + delete_warning
 		end
 
@@ -144,11 +157,8 @@ class AdminAction
 			end
 		end
 
-		def check_cat_jid
-			cat_jid = "catapult_jid-#{old_tel}"
-			REDIS.exists(cat_jid).then { |v|
-				EMPromise.reject(NilKey.new(cat_jid)) unless v == 1
-			}
+		def check_orphan
+			EMPromise.reject(Orphan.new) unless new_tel
 		end
 
 		def check_backend
diff --git a/test/test_admin_command.rb b/test/test_admin_command.rb
index 6d8ec8110287fe9193a9a77e045be1e800b77153..8cfb031aac872c6bc966ee7e43e95589a6d30be5 100644
--- a/test/test_admin_command.rb
+++ b/test/test_admin_command.rb
@@ -431,26 +431,181 @@ class AdminCommandTest < Minitest::Test
 	end
 	em :test_action_cancel_account_keep_number
 
-	def	test_change_num_for_unregistered_customer
-		execute_command { |exe|
-			sgx = Minitest::Mock.new(OpenStruct.new(
-				registered?: nil,
-				jid: Blather::JID.new(CONFIG[:sgx]) # Uses Bandwidth backend
-			))
-			target_customer = customer(sgx: sgx)
-			admin = AdminCommand.for(target_customer, exe.customer_repo)
+	def test_change_num_for_unregistered_customer
+		bandwidth_tn_repo_mock = setup_bandwidth_tn_repo_mock(
+			should_disconnect: false
+		)
 
-			error = assert_raises(
-				"number change for unregistered customer should raise"
-			) {
-				admin.action_number_change.sync
-			}
+		BandwidthTnRepo.stub :new, bandwidth_tn_repo_mock do
+			execute_command { |exe|
+				sgx = Minitest::Mock.new(OpenStruct.new(
+					registered?: false,
+					jid: Blather::JID.new(CONFIG[:sgx]) # Uses Bandwidth backend
+				))
+				target_customer = customer(sgx: sgx)
 
-			assert_equal error.to_s, "Customer not registered"
-		}
+				exe.customer_repo.expect(
+					:find_by_jid,
+					EMPromise.resolve(target_customer),
+					[Matching.new do |jid|
+						assert jid.is_a? Blather::JID
+						assert_equal jid.stripped.to_s, "test@example.com"
+					end]
+				)
+
+				AdminAction::NumberChange::REDIS.expect(
+					:get,
+					EMPromise.resolve(nil),
+					["jmp_customer_backend_sgx-test"]
+				)
+
+				AdminAction::NumberChange::REDIS.expect(
+					:get,
+					EMPromise.resolve(nil),
+					["jmp_customer_backend_sgx-test"]
+				)
+
+				AdminAction::NumberChange::REDIS.expect(
+					:del,
+					EMPromise.resolve(nil),
+					["jmp_customer_backend_sgx-#{target_customer.customer_id}"]
+				)
+
+				BackendSgx::IQ_MANAGER.expect(
+					:write,
+					EMPromise.resolve(nil)
+				) do |iq|
+					assert_ibr_deregister_form(iq)
+				end
+
+				BackendSgx::IQ_MANAGER.expect(
+					:write,
+					EMPromise.resolve(nil)
+				) do |iq|
+					assert_ibr_register_form(
+						iq,
+						"+12222222222"
+					)
+				end
+
+				BackendSgx::REDIS.expect(
+					:set,
+					EMPromise.resolve(nil),
+					["catapult_jid-+12222222222", "customer_test@component"]
+				)
+
+				expected_xadd_args = {
+					customer_id: "test",
+					old_tel: nil,
+					new_tel: "+12222222222",
+					should_delete: nil,
+					actor_id: "test",
+					class: "NumberChange",
+					direction: :forward
+				}.freeze
+
+				AdminActionRepo::REDIS.expect(
+					:xadd,
+					EMPromise.resolve(nil)
+				) do |admin_actions, star, **xadd_args|
+					assert_equal admin_actions, "admin_actions"
+					assert_equal star, "*"
+
+					xadd_args.each do |k, v|
+						assert_equal v, expected_xadd_args[k]
+					end
+				end
+
+				Command::COMMAND_MANAGER.expect(
+					:write,
+					EMPromise.resolve(change_number_form(
+						new_tel: "+12222222222"
+					))
+				) do |iq|
+					assert_undoable_form(iq)
+					assert_change_number_form(iq)
+				end
+
+				result = AdminCommand.for(
+					target_customer,
+					exe.customer_repo
+				).action_number_change.sync
+
+				slug, backend_report, number_report = result.lines
+
+				assert_equal slug.strip, "Action : Change Number"
+				assert_equal(
+					backend_report.strip,
+					"[move backend?]: sgx -> sgx"
+				)
+				assert_equal(
+					number_report.strip,
+					"[change number?]: nil -> +12222222222"
+				)
+
+				assert_mock Command::COMMAND_MANAGER
+				assert_mock exe.customer_repo
+				assert_mock AdminAction::NumberChange::REDIS
+				assert_mock AdminActionRepo::REDIS
+				assert_mock BackendSgx::REDIS
+				assert_mock BackendSgx::IQ_MANAGER
+				assert_mock bandwidth_tn_repo_mock
+				assert_mock sgx
+			}
+		end
 	end
 	em :test_change_num_for_unregistered_customer
 
+	def test_change_num_for_unregistered_customer_blank_new_tel
+		bandwidth_tn_repo_mock = setup_bandwidth_tn_repo_mock(
+			should_disconnect: false
+		)
+
+		BandwidthTnRepo.stub :new, bandwidth_tn_repo_mock do
+			execute_command { |exe|
+				sgx = Minitest::Mock.new(OpenStruct.new(
+					registered?: false,
+					jid: Blather::JID.new(CONFIG[:sgx]) # Uses Bandwidth backend
+				))
+				target_customer = customer(sgx: sgx)
+
+				exe.customer_repo.expect(
+					:find_by_jid,
+					EMPromise.resolve(target_customer),
+					[Matching.new do |jid|
+						assert jid.is_a? Blather::JID
+						assert_equal jid.stripped.to_s, "test@example.com"
+					end]
+				)
+
+				Command::COMMAND_MANAGER.expect(
+					:write,
+					EMPromise.resolve(change_number_form(
+						new_tel: ""
+					))
+				) do |iq|
+					assert_undoable_form(iq)
+					assert_change_number_form(iq)
+				end
+
+				result = assert_raises {
+					AdminCommand.for(
+						target_customer,
+						exe.customer_repo
+					).action_number_change.sync
+				}
+
+				assert_kind_of AdminAction::NumberChange::Orphan, result
+
+				assert_mock Command::COMMAND_MANAGER
+				assert_mock exe.customer_repo
+				assert_mock bandwidth_tn_repo_mock
+				assert_mock sgx
+			}
+		end
+	end
+	em :test_change_num_for_unregistered_customer_blank_new_tel
+
 	def test_change_num_same_num_same_backend
 		# Same as default given by `sgx.registered?` returned by `admin_command`
 		tel = "+15556667777"
@@ -473,12 +628,6 @@ class AdminCommandTest < Minitest::Test
 				end]
 			)
 
-			AdminAction::NumberChange::REDIS.expect(
-				:exists,
-				EMPromise.resolve(1),
-				["catapult_jid-#{tel}"]
-			)
-
 			Command::COMMAND_MANAGER.expect(
 				:write,
 				EMPromise.resolve(change_number_form(
@@ -526,12 +675,6 @@ class AdminCommandTest < Minitest::Test
 				end]
 			)
 
-			AdminAction::NumberChange::REDIS.expect(
-				:exists,
-				EMPromise.resolve(1),
-				["catapult_jid-#{tel}"]
-			)
-
 			Command::COMMAND_MANAGER.expect(
 				:write,
 				EMPromise.resolve(change_number_form),
@@ -625,12 +768,6 @@ class AdminCommandTest < Minitest::Test
 					["catapult_jid-#{new_tel}", "customer_test@component"]
 				)
 
-				AdminAction::NumberChange::REDIS.expect(
-					:exists,
-					EMPromise.resolve(1),
-					["catapult_jid-#{old_tel}"]
-				)
-
 				Command::COMMAND_MANAGER.expect(
 					:write,
 					EMPromise.resolve(change_number_form(
@@ -771,12 +908,6 @@ class AdminCommandTest < Minitest::Test
 					["jmp_customer_backend_sgx-#{target_customer.customer_id}"]
 				)
 
-				AdminAction::NumberChange::REDIS.expect(
-					:exists,
-					EMPromise.resolve(1),
-					["catapult_jid-+15556667777"]
-				)
-
 				BackendSgx::REDIS.expect(
 					:set,
 					EMPromise.resolve(nil),
@@ -899,12 +1030,6 @@ class AdminCommandTest < Minitest::Test
 					)
 				end
 
-				AdminAction::NumberChange::REDIS.expect(
-					:exists,
-					EMPromise.resolve(1),
-					["catapult_jid-#{old_tel}"]
-				)
-
 				AdminAction::NumberChange::REDIS.expect(
 					:rename,
 					EMPromise.resolve(nil),
@@ -1019,12 +1144,6 @@ class AdminCommandTest < Minitest::Test
 					end]
 				)
 
-				AdminAction::NumberChange::REDIS.expect(
-					:exists,
-					EMPromise.resolve(1),
-					["catapult_jid-#{old_tel}"]
-				)
-
 				AdminAction::NumberChange::REDIS.expect(
 					:rename,
 					EMPromise.resolve(nil),
@@ -1175,12 +1294,6 @@ class AdminCommandTest < Minitest::Test
 					[Blather::JID.new("test@example.com")]
 				)
 
-				AdminAction::NumberChange::REDIS.expect(
-					:exists,
-					EMPromise.resolve(1),
-					["catapult_jid-+15556667777"]
-				)
-
 				AdminAction::NumberChange::REDIS.expect(
 					:rename,
 					EMPromise.resolve(nil),