Replace exception on unknown DisconnectCause with UNKNOWN cause and message

Bug: 18681631
Change-Id: I99b6c049c0719d47c77c50743801ae2127ba4a86
diff --git a/src/com/android/services/telephony/DisconnectCauseUtil.java b/src/com/android/services/telephony/DisconnectCauseUtil.java
index 8f38ee1..0e9c0d0 100644
--- a/src/com/android/services/telephony/DisconnectCauseUtil.java
+++ b/src/com/android/services/telephony/DisconnectCauseUtil.java
@@ -132,7 +132,10 @@
                 return DisconnectCause.UNKNOWN;
 
             default:
-                throw new IllegalStateException("Unrecognized Telephony DisconnectCause");
+                Log.w("DisconnectCauseUtil.toTelecomDisconnectCauseCode",
+                        "Unrecognized Telephony DisconnectCause "
+                        + telephonyDisconnectCause);
+                return DisconnectCause.UNKNOWN;
         }
     }