A method is provided for routing mobile telephone short text messages between different mobile telephone messaging networks, including mobile telephone messaging networks operated by a single carrier (i.e., intra-carrier messaging) or by different carriers (i.e., inter-carrier messaging). The method includes receiving a short
text message at a mobile telephone short message gateway operated by a first mobile telephone carrier, the short
text message having a destination
directory number (DN). The short message gateway determines that the destination
directory number (DN) is associated with one of two or more mobile telephone networks. The two or more mobile telephone networks may be operated by the first mobile telephone carrier alone or by the first mobile telephone carrier and another carrier. The short
text message is then routed to the appropriate mobile
telephone network based upon its destination
directory number (DN). In a particular implementation, the short text message is a
Short Message Service (SMS) message, and the short message gateway is a Short Message
Peer to Peer (SMPP) gateway. The routing of the SMS includes reformatting it to include a
Simple Mail Transfer Protocol (SMTP) address of an SMPP gateway of the mobile telephone messaging network to which the SMS message is directed. The SMS message is then sent as an SMTP message over
the Internet.