Systems and methods are disclosed for interfacing SMS/MMS web applications with packet-switched networks. One embodiment comprises a system that handles a Mobile Terminated (MT) text message from a web application to a packet-switched network. The system receives a send command for the MT text message from the web application. The send command is based on a standard used by the web application, such as Parlay X. The system converts the send command for the MT text message to a SIP send request, and transmits the SIP send request for the MT text message to a packet-switched network for delivery to a recipient.