diff --git a/README.variables b/README.variables
index 86c7ca7824..95485ba7fb 100755
--- a/README.variables
+++ b/README.variables
@@ -44,7 +44,7 @@ ${UNIQUEID}	Current call unique identifier
 ${DNID}         Dialed Number Identifier
 ${RDNIS}        Redirected Dial Number ID Service
 ${HANGUPCAUSE}	Hangup cause on last PRI hangup
-${SIPDOMAIN}    SIP domain (if appropriate)
+${SIPDOMAIN}    SIP destination domain of an inbound call (if appropriate)
 
 There are two reference modes - reference by value and reference by name. 
 To refer to a variable with its name (as an argument to a function that 
diff --git a/doc/README.variables b/doc/README.variables
index 86c7ca7824..95485ba7fb 100755
--- a/doc/README.variables
+++ b/doc/README.variables
@@ -44,7 +44,7 @@ ${UNIQUEID}	Current call unique identifier
 ${DNID}         Dialed Number Identifier
 ${RDNIS}        Redirected Dial Number ID Service
 ${HANGUPCAUSE}	Hangup cause on last PRI hangup
-${SIPDOMAIN}    SIP domain (if appropriate)
+${SIPDOMAIN}    SIP destination domain of an inbound call (if appropriate)
 
 There are two reference modes - reference by value and reference by name. 
 To refer to a variable with its name (as an argument to a function that