Abstract: A prepaid messaging solution which uses open networking standards (e.g., TCP/IP) and which supports pre-payment of enhanced Internet messaging services. The disclosed prepaid architectures and methods accurately determine if a subscriber has sufficient account balance to deliver a complete short message, prior to delivery of the message. The short message may be prevented from being delivered (either at the source end or at the destination end) if insufficient funds are in the subscriber's account. A prepaid tariff engine is preferably extensible over a TCP/IP network, and supports remote interaction with the SMSC and web chat servers for the purpose of applying a real-time billing charge for each message. A service provider may create subscriber classes of service that define and uniquely identify subscriber rate and/or tariffing plans used to apply real-time billing charges for sending or receiving of messages. The prepaid short message tariff engine determines the appropriate message billing based upon, e.