diff --git a/doc/README.variables b/doc/README.variables
index b703b54ae4..d145a21764 100755
--- a/doc/README.variables
+++ b/doc/README.variables
@@ -75,6 +75,9 @@ ${TIMESTAMP}	Current date time in the format: YYYYMMDD-HHMMSS
 ${TXTCIDNAME}	Result of application TXTCIDName
 ${UNIQUEID}	Current call unique identifier
 
+NOTE: Attempting to set any of these "special" variables will not change 
+      their value, but will not display any warning either.
+
 The dial() application sets the following variables:
 
 ${DIALEDPEERNAME} Dialed peer name