A method is disclosed for delivering a short message from an external short message entity (ESME) to a wireless device. The method comprises transmitting a message from a message source device such as an external short message entity to a gateway, the message being associated with a service type. A routing determination is made based on the service type associated with the message. The message is then routed to one of a plurality of message centers according to the routing method chosen. The method may be used with a gateway system that implements a standard interface to a message complex of a wireless system. The interface enables all ESMEs to communicate with the message complex using a consistent standard interface. The system used to implement the method of the present invention comprises a short message point-to-point gateway, a message complex, a home location register and a mobile switching center. The external short message entity connects to the short message point-to-point gateway and requests delivery of a message to a wireless device, and the short message point-to-point gateway routes the request to an appropriate message center.