diff --git a/test/property/test_webhook_handler.rb b/test/property/test_webhook_handler.rb
index 1b7046e0d796c86f8f419349fa2694ca1f28df4f..dbb649a5b4be53944df7e2b7962a34370509f867 100644
--- a/test/property/test_webhook_handler.rb
+++ b/test/property/test_webhook_handler.rb
@@ -355,4 +355,54 @@ class WebhookPropertyTest < Minitest::Test
 		}
 	end
 	em :test_inbound_empty_text_no_media_returns_400
+
+	def test_inbound_unknown_type_sends_notification
+		property_of {
+			Webhook
+				.new(REDIS)
+				.type { "unknown" }
+				.direction { "in" }
+				.message { |registered, jid, dir, top_level_to|
+					Message
+						.new(REDIS)
+						.to { [nanpa_phone] }
+						.generate(registered, jid, dir)
+				}
+				.generate
+		}.check { |metadata, example|
+			result = invoke_webhook(example)
+			assert_equal 200, result[0]
+			assert_equal 1, written.length
+
+			msg = written.shift
+			assert_kind_of Blather::Stanza::Message, msg
+			assert_equal(
+				metadata["jid"],
+				msg.to.to_s,
+				"Notification should be sent to customer's jid"
+			)
+
+			expected_from = example["message"]["from"]
+			unless expected_from.start_with?("+")
+				expected_from += ";phone-context=ca-us.phone-context.soprani.ca"
+			end
+			assert_equal(
+				"#{expected_from}@#{ARGV[0]}",
+				msg.from.to_s,
+				"Notification should be from sender's Cheogram jid"
+			)
+
+			expected_text = "unknown type (unknown)" \
+				" with text: #{example["message"]["text"]}"
+			assert_equal(
+				expected_text,
+				msg.body,
+				"Body should contain the unknown type and original text"
+			)
+
+			entries = REDIS.stream_entries("messages").sync
+			assert_empty entries, "Unknown inbound type should not emit a stream event"
+		}
+	end
+	em :test_inbound_unknown_type_sends_notification
 end