Monthly bill for call charges

Hope everyone is doing well. I need to understand something about the ASTPP postpaid billing invoice.

Basically I create account and I set billing date 1.

What I want to do is ASTPP will be create the call charges for the previous month automatically by the cron.

Anyway my cron is not working.

I know there is a bug maybe.

But I try to generate invoice manually from the billing page and I put call charges as description but I can see invoice is generated also the account balance is increased as well.

Is there any way I can generate invoice manually for the call charges or it’s need to be custom development?

Because the plan is when I general invoice protocol charges it will be not changed the call charges balance I mean the account balance.