Here contains a list of destination codes and billing parameters for each of them.
Each destination code has its independent change history of billing parameters and activation date for each change.
In case if you need to schedule some change for destination code - it's recommended to add new change in change history with needed activation date and set needed billing parameters inside it.
Therefore, if later needed, you can do Billing re-calculation for this period and system will correctly re-calculate calls with new billing parameters as well as with old ones.
In case if you will change billing parameters in current price-list, basing on which some CDR have been already stored, then ,when doing Billing re-calculation, all CDR matching to activation time of price-list, will be re-calculated with new billing parameters and you won't be able to restore old billing parameters, basing on which this calls have been stored originally.
An exception from this is typo when filling change history.
In this case you should fix typo and then perform Billing re-calculation, in case if some calls have been stored with wrong billing parameters.
It's possible to automatically import from attachments which come with e-mails from you partner (see Prices by e-mail)