Method and system for messaging across cellular networks and a public data network

A computer program product residing on a computer readable medium, the computer readable medium residing on a server in data communication with a short message service center and an instant message system, the computer program product comprising:

• a database comprising a plurality of user profiles, each of the plurality of user profiles further comprises user identification information and at least one of an instant message has name or an instant message function assigned to a user destination address;
• a component for receiving an instant text message signal from at least one cellular communications device via a mobile carrier and the short message service center, the received instant text message signal comprises a destination address, information associated with the cellular communications device's user, message content and message address;
• a component for executing the assigned instant message function with an instant message server through the public data network according to the information contained in the message content, if the destination address is assigned to an instant message function;
• and
• a component for creating an instant text message comprising the message content for delivery to the assigned instant message user name, if the destination address is assigned to an instant message user name.