Each pricelist contains:
In case if you need to add change to pricelist - it's recommended to insert a new pricelist with needed activation time and specify in it needed billing parameters.
Therefore, if later you'll need, you can perform Billing re-calculation for this period and system will correctly re-calculate calls with old billing parameters and with new 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 price-list.
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.