Analysis of Variables in Expressions
If you would like to analyze a variable or system function (e.g. in the blocks “Evaluate” or “Choose Announcement”, you can compare a variable with an expression.
This expression can contain all the userdefined variables of this script as well as all system functions. The expressions used here are created in the syntax of Visual Basic Script:
A variable can be either a sequence of characters (“3”) or a numeric value (3).
It is possible to link variables.
The expression
=“Call from the number” & CallerNumber()
during the call handling of a call from the number 0123456789, will result in
Call from the number 0123456789
Calculation operation with variables
The expression
a=3*b
will be numerically evaluated so that a will be assigned the result of the calculation operation. This requires that b contains a numeric value or a string, which is interpretable as a numeric value.
Addition
This operation is executed depending on the type of variable. The expression
=”3” + CalledNumber()
results, during the treatment of a call with CalledNumber()=234, in a string in the form
"3234".
The expression
= 3 + CalledNumber()
results, during the treatment of a call with CalledNumber()=234, in a numeric value
237

If the variable or a system function (here CalledNumber()) contains a string, which is not interpretable as a numeric value, then this expression will generate an error (type mismatch) and the call will be terminated.

Comparison
This operation runs analogous to Addition. Thus, the expression generates
"333" > CalledNumber()
a comparison of the strings.
If the variables to be compared are strings, they will be compared as ASCII strings (standard string comparison) starting with the first character. The first discrepency (> or <) determines the result.
Example:
The following strings exist: "A"=65; "a"=97; "b"=98; "c"=99.
Then the following apply:
"aab" < "aac", because 1st character a=a; 2nd character a=a; 3rd character b<c
"aab" > "aAc", because 1st character a=a; 2nd character a>A
The expression
333 > CalledNumber()
compares the numeric value. In this case it is once again necessary that the system function contains a numeric value.