diff --git a/rtvi-client-android/build.gradle.kts b/rtvi-client-android/build.gradle.kts
index 853e83e..2ee6d0a 100644
--- a/rtvi-client-android/build.gradle.kts
+++ b/rtvi-client-android/build.gradle.kts
@@ -99,6 +99,8 @@ signing {
     val signingKey = System.getenv("RTVI_GPG_SIGNING_KEY")
     val signingPassphrase = System.getenv("RTVI_GPG_SIGNING_PASSPHRASE")
 
-    useInMemoryPgpKeys(signingKey, signingPassphrase)
-    sign(publishing.publications)
+    if (!signingKey.isNullOrEmpty() || !signingPassphrase.isNullOrEmpty()) {
+        useInMemoryPgpKeys(signingKey, signingPassphrase)
+        sign(publishing.publications)
+    }
 }
\ No newline at end of file
diff --git a/rtvi-client-android/src/main/java/ai/rtvi/client/VoiceEventCallbacks.kt b/rtvi-client-android/src/main/java/ai/rtvi/client/VoiceEventCallbacks.kt
index 2554ae4..f0fed77 100644
--- a/rtvi-client-android/src/main/java/ai/rtvi/client/VoiceEventCallbacks.kt
+++ b/rtvi-client-android/src/main/java/ai/rtvi/client/VoiceEventCallbacks.kt
@@ -5,6 +5,7 @@ import ai.rtvi.client.types.MediaDeviceInfo
 import ai.rtvi.client.types.Participant
 import ai.rtvi.client.types.PipecatMetrics
 import ai.rtvi.client.types.ServiceConfig
+import ai.rtvi.client.types.Tracks
 import ai.rtvi.client.types.Transcript
 import ai.rtvi.client.types.TransportState
 
@@ -127,6 +128,11 @@ abstract class VoiceEventCallbacks {
      * Invoked when the state of the input devices changes.
      */
     open fun onInputsUpdated(camera: Boolean, mic: Boolean) {}
+
+    /**
+     * Invoked when the set of available cam/mic tracks changes.
+     */
+    open fun onTracksUpdated(tracks: Tracks) {}
 }
 
 internal class CallbackInterceptor(vararg listeners: VoiceEventCallbacks): VoiceEventCallbacks() {
@@ -224,4 +230,8 @@ internal class CallbackInterceptor(vararg listeners: VoiceEventCallbacks): Voice
     override fun onInputsUpdated(camera: Boolean, mic: Boolean) {
         callbacks.forEach { it.onInputsUpdated(camera = camera, mic = mic) }
     }
+
+    override fun onTracksUpdated(tracks: Tracks) {
+        callbacks.forEach { it.onTracksUpdated(tracks) }
+    }
 }
\ No newline at end of file