The present invention provides systems and methods for allowing access to a voice mailbox associated with a pre-paid mobile phone subscriber's account after the expiration of the subscriber's credits. A call processing system may be configured to receive a call from a calling party and to connect the call to a voice mailbox system. The call processing system may allow the calling party to record a voice message that can subsequently be accessed by the subscriber for an access fee. The call processing center may also be configured to allow the calling party to add credit to the subscriber's account. Access fees are paid and credits are added to the account by way of pre-paid calling cards, smart cards, credit cards, debit cards, electronic fund transfers.