[Freeswitch-users] Pre-paid impossible with freeSwitch ?

Hello, I am trying to make a Pre-Paid or Advanced billing method for test. But i applied Javascript with FS. - In my test i am running calls for 3 or 4 hours - With a billing per minute of 10 US Dollar Now those calls balance is -200 or -300, how can i tell FS via javascript please kindly stop it because its crossing the limit. Is there any way to manage it ? Thanks & Regards