There could be several ways to call different XML APIs to add the balance on customer's account. This is just one of those flows/methods which is mentioned here.

In order to add the balance on the customer's account first thing which you will need to know is the denomination /topup values which are allowed to be added on the account to get that list you call GetDenomination XML API. Below are the required fields in the GetDenomination XML API

Above mentioned fields can be obtained using the the GetCustomerInfo XML API

After you call the GetDenomination XML API you will have a list of the denomination /topup values which can be added on the customer's account. After you select the topu up value which needs to be added you will also need to know the tax to be charged for that you call GetTaxDetail XML API

Finally when you have the total amount to be charged you have two options:

1. . Call the Payment XML API followed by AddBalance API or
2. Call AddBalancewithPaymentBelow is the sample request for AddBalancewithPayment.You get the CUSTOMERID and CARRIER CODE from GetCustomerInfo

Upon the success response the topup amout is applied to the customer's account.