diff --git a/app/src/test/kotlin/io/flamenet/messenger/app/SecondDeviceCallTest.kt b/app/src/test/kotlin/io/flamenet/messenger/app/SecondDeviceCallTest.kt
new file mode 100644
index 0000000..f0c8692
--- /dev/null
+++ b/app/src/test/kotlin/io/flamenet/messenger/app/SecondDeviceCallTest.kt
@@ -0,0 +1,62 @@
+package io.flamenet.messenger.app
+
+import java.io.File
+import kotlin.test.Test
+import kotlin.test.assertFalse
+import kotlin.test.assertTrue
+
+/**
+ * One account on two devices: a ring on the second must not end a call that
+ * was answered on the first.
+ *
+ * `CallManager` needs WebRTC, which the JVM test runtime does not have, so this
+ * reads the source the way the iPhone's `RingTimesOutTests` does. That iPhone
+ * test reads this file as well, but only when the two checkouts sit side by
+ * side under the directory names it expects, which a CI build directory never
+ * has. This copy is the one that actually runs on every Android pipeline.
+ */
+class SecondDeviceCallTest {
+    private val source: String by lazy {
+        listOf(
+            "src/main/kotlin/io/flamenet/messenger/app/CallManager.kt",
+            "app/src/main/kotlin/io/flamenet/messenger/app/CallManager.kt",
+        ).map(::File).first { it.exists() }.readText()
+    }
+
+    /** The function starting at [marker], up to the next one. */
+    private fun body(marker: String): String {
+        val start = source.indexOf(marker)
+        assertTrue(start >= 0, "no $marker in CallManager.kt")
+        val rest = source.substring(start + marker.length)
+        val end = rest.indexOf("private fun ").let { if (it < 0) rest.length else it }
+        return rest.substring(0, end)
+    }
+
+    @Test
+    fun `the ring guard releases the ring without telling the caller`() {
+        val guard = body("private fun armRingGuard()")
+        assertTrue(guard.contains("notifyPeer = false"), "the guard must not message the caller")
+        // Bounded to the guard: the connect guard below it still, correctly,
+        // hangs up with notifyPeer = true.
+        assertFalse(
+            guard.contains("notifyPeer = true"),
+            "a timeout sent from a second device hangs up a call answered on the first",
+        )
+    }
+
+    @Test
+    fun `an end hangs up only its own call, and not once that call has connected`() {
+        val start = source.indexOf("Content.CallSignal.END ->")
+        assertTrue(start >= 0, "no end branch in onSignal")
+        val branch = source.substring(start, minOf(source.length, start + 2000))
+        assertTrue(
+            branch.contains("incoming.callId != current?.callId"),
+            "an end for another call must not hang this one up",
+        )
+        assertTrue(branch.contains("setOf(\"declined\", \"busy\", \"timeout\")"))
+        assertTrue(
+            branch.contains("state == State.CONNECTING || state == State.ACTIVE"),
+            "only a call that has connected may ignore them; a ringing one must still stop",
+        )
+    }
+}