How to create products and bill clients in Porta Billing.
– Product Name, Selling Price, Subscription Plans, Products Setup, Volume Discount Plans, Periodic Payments

Each Product in Porta can be tagged to a monthly subscription fee, online sign-up, rate file or tariff, volume discount plan (or free minutes used for “unlimited plans”).

Subscription Plan allows you to charge a fixed amount per month for an example $19.95 per month. 

Periodic Payments is a feature that permits you to automatically charge your customers credit card automatically. 
This can be done monthly (at a certain date for an example 30th of every month) or based on their balance (example: when balance falls below $30, charge $20). 

Volume Discount Plan is what allows you sell a plan that resets every month.  
You can create subscription plans for an example $19.95 per month and it allows clients to call say 1000 minutes per month to select destinations by prefix and area code.

You need to advise us if the incoming minutes are free, how much you wish to charge your customers for destinations they are calling. 
All destinations are dialed by country code and number (e.164 compliant). There is no need to dial any access code. 
If you wish to have access codes, you can implement your own dialing plan by customer using the wizard in your reseller login.
If you plan to restrict phone prefix or destinations that they can dial, we need to remove those destinations from the product tariff.

Globalink-Worldkom Private Label VoIP Reseller Support