In a Cally Square project you are able to use most of the PHP function to manipulate a string variable such as the CallerID.
For example, we want to check the international prefix and send the call to the related country queue.
If the callerID starts with 012 we send the call to the queue 1, if anything else to the queue 2.
We can simply check the callerID using the php function substr (http://php.net/manual/en/function.substr.php) in a MATH block and check the result with a GOTOIF block
For example, the callerId is 0123456789.
The substr function result will be 012 (first 3 digit) and it is saved into the RESULT variable.
In the GOTOIF block just check the RESULT variable.