TECHNIQUE FOR ENABLING MESSAGING SYSTEMS TO USE ALTERNATIVE MESSAGE DELIVERY MECHANISMS

A method, system, and computer program product for enabling messaging systems to use alternative message delivery mechanisms. In existing instant messaging systems, messages cannot be delivered to an intended recipient unless the recipient is currently logged on to an instant messaging system. According to the present invention, users may register one or more alternative message delivery mechanisms (such as pagers, cell phones, etc.) through which they are available as an alternative to an instant messaging system. Constraints may optionally be added to these registered alternatives, such as specifying a limitation on days of the week and/or hours of the day when a particular alternative may be used. Providing that an alternative messaging mechanism is registered, and any constraints for this alternative are satisfied, in the first preferred embodiment the extended IMS will select a suitable alternative and deliver the message. In a second and third preferred embodiment, the sender of the “instant” message will be informed of the available alternative(s). The sender may then choose to have his message delivered even though the intended receiver is not currently logged on to an instant messaging system. Fourth and fifth embodiments enable a message to be delivered to a recipient using a registered mechanism (that may include an IMS), and provide for determining availability of a selected user. Using these techniques, the real-time awareness of potential message receivers in instant messaging systems is extended.