diff --git a/telephony/java/android/telephony/UiccSlotInfo.java b/telephony/java/android/telephony/UiccSlotInfo.java
index 785d7aea2a6fd..fb1da7b12556e 100644
--- a/telephony/java/android/telephony/UiccSlotInfo.java
+++ b/telephony/java/android/telephony/UiccSlotInfo.java
@@ -140,6 +140,14 @@ public class UiccSlotInfo implements Parcelable {
         return mIsEuicc;
     }
 
+    /**
+     * Returns the ICCID of the card in the slot, or the EID of an active eUICC.
+     * <p>
+     * If the UICC slot is for an active eUICC, returns the EID.
+     * If the UICC slot is for an inactive eUICC, returns the ICCID of the enabled profile, or the
+     * root profile if all other profiles are disabled.
+     * If the UICC slot is not an eUICC, returns the ICCID.
+     */
     public String getCardId() {
         return mCardId;
     }