##### Periodic service

Periodic service properties window consists of two pages:

- Main (standard, see above).
- Service parameters. Includes the following elements:
  - Periodic fee is the fixed price of the service per one accounting period. Services of specialized types may have some other components of price besides this one, namely, the price per unit of traffic or per connection time, etc.
  - Charge method is the order of charging off the user’s account. The possible values are:
  - At the beginning of the period means that the charge-off is done at one instant on creation of the service link;
  - At the end of the period means that the charge-off is done at once immediately before the closing of the accounting period (the one associated with the service link);
  - Flow method means that the charge-off is done in portions during the whole length of the accounting period. The number of portions is determined by the corresponding parameter of the accounting period, if it is set, or by the core settings otherwise (the`flow_discounts_per_period` parameter).
- Charge policy is the default charge policy that will be used for service link creation for this service.

  If the number of charge-offs per week is not set in the accounting period properties, the period is divided into equal parts anyway, but the number of parts is given by the `flow_discounts_per_period` system parameter (by default 64). At the end of each part the event handler runs through all periodic services linked to this period and having flow method of charging. For every such service, the amount to be charged is determined, and if it exceeds the `discount_barrier` parameter, the charge-off is made.

  - Start date is the date when the provision of service begins. Used for purely information purposes.
  - End date is the optional date when the service is shut down and removed altogether, unless it has some service links attached to it.

  All these parameters are also relevant for services of other types, which however possess a number of extra parameters specific to each type.

  Parameters of the corresponding service link are described in Periodic service link.