A messaging system for a wireless network may be constructed using a gateway architecture in which a number of messaging servers are connected to external networks through the gateway. In one implementation, a method implemented in the system may include receiving a message that is communicated as part of a messaging protocol for delivering text or multimedia messages to user devices and altering the message to include a billing identifier describing how the message should be billed. The message may be altered by the gateway and may be transmitted to a messaging server for extraction of the billing information.