Abstract: A method is disclosed such that when a call is being set up from or to a mobile (or fixed) pre-paid subscriber, a portion of the value in the subscriber's pre-paid account is withdrawn to cover the cost of the call. Preferably, the amount withdrawn is large enough to cover the cost for a call of typical duration (e.g., 4 minutes). At call set up, for example, in an Intelligent Network, this amount is withdrawn from the account and allocated to the call being set up. If this amount is not completely used up, the remainder is returned to the pre-paid account. If, however, the allocated amount is depleted before the call is completed, a second allocation or withdrawal from the account is requested for that call. If the value left in the account is large enough to cover the second withdrawal request, a second amount is withdrawn and allocated to cover the ongoing call. If needed, additional withdrawals can be made to cover the ongoing call until it is completed.