diff --git a/doc/README.variables b/doc/README.variables
index ced8f8e90310d675bd3f9ceda6e61c342c8f1559..c02a94af4a3bcf73bc6e5811b9445a858145963f 100755
--- a/doc/README.variables
+++ b/doc/README.variables
@@ -78,6 +78,9 @@ ${TXTCIDNAME}	Result of application TXTCIDName
 ${UNIQUEID}	Current call unique identifier
 ${PRIREDIRECTREASON} Reason for redirect, if a call was directed
 
+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