$isNull
Check whether the specified SIP header, property variable or DialPlan method is null.
Syntax:
$isNull( name )
Parameters:
name – the name of the SIP header, property variable or DialPlan method.
Returns:
true – if the specified SIP header, variable or DialPlan method is null.
false – otherwise
Version Since:
2.4
Where the function can be used:
- Preliminary rules
- Regular rules
Example:
$isNull("$getSIPuser(From)”) = true
If the From-URI doesn’t have a user-part.
$isNull( “&my.val” ) = false
If the variable “my.val” is not null.