communication server 100 provides the list of contacts of a user to the registered endpoints of that user an example of such endpoints includes client a 150 and client b 175 which may both be associated with human users in some embodiments the clients 150 and 175 include a communication application 155 the communication application 155 may contain a subscribe component 160 a registration component 165 and a user interface component 170 the subscribe component 160 subscribes to the presence information of the user 39 s contacts the registration component 165 registers the endpoint of the user with the live communication server 100 and publishes updates to the user 39 s presence information the user interface component 170 may provide windows views and other graphical elements that are presented to the user while interacting with the communication application 155 the facility may be associated with a pstn network 130 through which telephones 180 and 190 associated with each client can communicate the telephones 180 and 190 may also each be associated with a legacy pbx 185 and 195 as needed a remote call control rcc server 196 may provide an interface between the pbx or other pstn component and the client computing devices in this way the client computing devices are made aware of activities occurring at the pbx where a call is being placed for example the remote call control server may serve as gateway to convert the standard protocol used by the communication application to the specific computer telephony integration cti protocol supported.