diff --git a/telephony/java/com/android/ims/internal/IImsCallSessionListener.aidl b/telephony/java/com/android/ims/internal/IImsCallSessionListener.aidl
index acd1eb9d592e7..11da6e6aa547b 100644
--- a/telephony/java/com/android/ims/internal/IImsCallSessionListener.aidl
+++ b/telephony/java/com/android/ims/internal/IImsCallSessionListener.aidl
@@ -104,4 +104,14 @@ interface IImsCallSessionListener {
             in int srcAccessTech, in int targetAccessTech, in ImsReasonInfo reasonInfo);
     void callSessionHandoverFailed(in IImsCallSession session,
             in int srcAccessTech, in int targetAccessTech, in ImsReasonInfo reasonInfo);
+
+    /**
+     * Notifies the TTY mode change by remote party.
+     * @param mode one of the following:
+     * - {@link com.android.internal.telephony.Phone#TTY_MODE_OFF}
+     * - {@link com.android.internal.telephony.Phone#TTY_MODE_FULL}
+     * - {@link com.android.internal.telephony.Phone#TTY_MODE_HCO}
+     * - {@link com.android.internal.telephony.Phone#TTY_MODE_VCO}
+     */
+    void callSessionTtyModeReceived(in IImsCallSession session, in int mode);
 }