HTTP SMS API - billing
(available in version: Ozeki
NG SMS Gateway v3.0.1 or newer)
The billing system allows you to set credit limits for each user. This is a
good option if you want to do billing and accounting. It is also useful for
cost control. The following methods can be used to manage user credit limits.
Please note that the credit limit of a user can only be modified by the
administrator account (admin).