Calcuration of voice call fee for my customer from CDR - repost

I have several customers using its voice over IP service. Its customer’s phones are connected to other voice carrier’s system. The voice carrier produced Call Detail Record, which contains call record with call destination, charge period for each call, and call fee for the call. I need to charge its customer based on its own call rate, and in order to do so, I need to calculate billing based on the CDR provided by the carrier company. I already have software developed for this purpose. It is developed with php software to automatically calculate call fee for its customer; however, the software does not support charge period other than 60 seconds. It is required to use open source voip billing platform that is already developed by 3rd party. Required work: I will give you CDR and rate table. Please establish billing software with CDR importing platform to my ubuntu server in my office. When I confirm that the new billing is created with the CDR successfully, I will pay.