diff --git a/app/src/main/kotlin/io/flamenet/messenger/app/MainActivity.kt b/app/src/main/kotlin/io/flamenet/messenger/app/MainActivity.kt
index 7afe9aa..514a4b3 100644
--- a/app/src/main/kotlin/io/flamenet/messenger/app/MainActivity.kt
+++ b/app/src/main/kotlin/io/flamenet/messenger/app/MainActivity.kt
@@ -734,6 +734,18 @@ internal fun ColumnScope.SignedIn(
         )
     }
 
+    // A call refused because the peer's keys changed offers the review here,
+    // rather than telling somebody to go and find the conversation (ios#73).
+    // Compare and accept both live behind this, in the banner the chat already
+    // draws, so the wording it is judged by is unchanged.
+    if (phase.callKeyReview != null) {
+        KitSecondaryButton(
+            text = "Review their security code",
+            onClick = { model.reviewBlockedCallKeys() },
+            tag = "review-call-keys",
+        )
+    }
+
     if (addingContact) {
         AddContactForm(model, phase, initial = scannedPrefill) {
             addingContact = false
diff --git a/app/src/main/kotlin/io/flamenet/messenger/app/MessengerViewModel.kt b/app/src/main/kotlin/io/flamenet/messenger/app/MessengerViewModel.kt
index 525680e..4517ec3 100644
--- a/app/src/main/kotlin/io/flamenet/messenger/app/MessengerViewModel.kt
+++ b/app/src/main/kotlin/io/flamenet/messenger/app/MessengerViewModel.kt
@@ -124,6 +124,11 @@ class MessengerViewModel(
             val lookupMiss: String? = null,
             /** The call in progress, if any (§8.10). */
             val call: CallState? = null,
+            /**
+             * The peer whose key change blocked a call, so the failure can
+             * offer the review instead of describing it (ios#73).
+             */
+            val callKeyReview: Pair<Long, String>? = null,
             /** Shown once, before the first call ever placed on this device. */
             val callPrivacyPrompt: Long? = null,
             /**
@@ -383,6 +388,17 @@ class MessengerViewModel(
         }
     }
 
+    /**
+     * Open the conversation with the peer whose key change blocked a call, and
+     * clear the failure (ios#73).
+     */
+    fun reviewBlockedCallKeys() {
+        val current = _phase.value as? Phase.SignedIn ?: return
+        val (peerId, peerName) = current.callKeyReview ?: return
+        _phase.value = current.copy(error = null, callKeyReview = null)
+        openChat(peerId, peerName)
+    }
+
     fun signIn(
         handle: String,
         passphrase: String,
@@ -2272,10 +2288,10 @@ class MessengerViewModel(
                                         it.copy(
                                             call = null,
                                             error =
-                                                "Their security code changed, so the call " +
-                                                    "was not placed. Open the conversation with " +
-                                                    "${nameFor(it, peerId)} to review it, then " +
+                                                "Their security code changed, so the call was " +
+                                                    "not placed. Review the change before you " +
                                                     "call again.",
+                                            callKeyReview = peerId to nameFor(it, peerId),
                                         )
                                     }
                                 }
diff --git a/app/src/test/kotlin/io/flamenet/messenger/app/CallKeyReviewTest.kt b/app/src/test/kotlin/io/flamenet/messenger/app/CallKeyReviewTest.kt
new file mode 100644
index 0000000..dc86a4d
--- /dev/null
+++ b/app/src/test/kotlin/io/flamenet/messenger/app/CallKeyReviewTest.kt
@@ -0,0 +1,68 @@
+package io.flamenet.messenger.app
+
+import java.io.File
+import org.junit.Assert.assertFalse
+import org.junit.Assert.assertTrue
+import org.junit.Test
+
+/**
+ * A call refused because the peer's keys changed offers the review (ios#73).
+ */
+class CallKeyReviewTest {
+    private fun source(path: String): String {
+        val file = File("src/main/kotlin/io/flamenet/messenger/app/$path")
+        assertTrue("missing $path", file.exists())
+        return file.readText()
+    }
+
+    /** The blocked peer is carried, not just named in a sentence. */
+    @Test
+    fun theBlockedPeerIsCarried() {
+        val vm = source("MessengerViewModel.kt")
+        assertTrue(
+            "the failure must carry the peer",
+            vm.contains("val callKeyReview: Pair<Long, String>? = null"),
+        )
+        assertTrue(
+            "and be set where the trust gate refuses the signal",
+            vm.contains("callKeyReview = peerId to nameFor(it, peerId)"),
+        )
+    }
+
+    /** Tapping it opens that conversation and clears the failure. */
+    @Test
+    fun reviewOpensTheConversation() {
+        val vm = source("MessengerViewModel.kt")
+        assertTrue(vm.contains("fun reviewBlockedCallKeys()"))
+        assertTrue("must open the chat", vm.contains("openChat(peerId, peerName)"))
+        assertTrue(
+            "and must not leave the failure on screen",
+            vm.contains("copy(error = null, callKeyReview = null)"),
+        )
+    }
+
+    /** The button is on the screen the failure appears on. */
+    @Test
+    fun theButtonIsRendered() {
+        val main = source("MainActivity.kt")
+        assertTrue(main.contains("phase.callKeyReview != null"))
+        assertTrue(main.contains("model.reviewBlockedCallKeys()"))
+        assertTrue(main.contains("\"review-call-keys\""))
+    }
+
+    /**
+     * The reason is still named. A generic "call failed" was the original
+     * complaint, and the fix must not regress into one.
+     */
+    @Test
+    fun theReasonIsStillNamed() {
+        val vm = source("MessengerViewModel.kt")
+        assertTrue(vm.contains("Their security code changed"))
+        // The quoted form only: the KDoc on reviewBlockedCallKeys describes
+        // opening a conversation, and that is not copy anybody reads.
+        assertFalse(
+            "must not tell somebody to go and find the conversation themselves",
+            vm.contains("\"Open the conversation with "),
+        )
+    }
+}