Requests for communications and for establishing communication sessions with an intended addressee are detected and notifications regarding the pending communication request are provided to the intended addressee. If the addressee is operating on-line in an IP environment, the messages are delivered to the addressee via a real-time mechanism. However, if the addressee is not operating on-line in an IP environment, a message is sent via an alternate means, such as SMS, email etc. For on-line addressees, if the addressee is presently running an application program, the type of application program can be ascertained and the notification message can be compatible with the rendering functions of the application program.