Abstract: Users access an on-line address service to register their name (which may be a pseudonym or other fictitious or imaginary identity) and a unique contact address that may be used directly or indirectly to address a message over another communication network to an associated listening device. Once a potential user has registered his on-line identity and contact information, other users accessing the address service can then designate one of the listed names, either by selecting the name from a display list of registered names (if all registered names are displayed) or by entering the designated name onto an appropriate form, whereupon the computer hosting the address service will broadcast a message addressed to the identified person's associated listening device. Once the message is received, the listening device notifies the associated user by causing the user's computer to initiate an appropriate visual and/or audio alert display concerning the contact attempt.