An OCS (Online Charging System) https://www.onlinechargingsystem.com/ has become an integral part of telecom billing as it allows for both event based and session based charging in real time. It calculates charges for a particular call on the basis of CDRs (Call Data Record) and updates the result on the billing system. This telecom charging system is capable of handling account balance of subscribers, ensuring credit limits and authorizing resources on the basis of transactions.