A method and apparatus for establishing a voice call to a PSTN extension for a networked client computer, and routing the voice call off of the network, is provided. In a first embodiment, the apparatus comprises a storage medium having stored therein a plurality of programming instructions for implementing a set of communication services for facilitating establishment of the voice call to the PSTN extension, and an execution unit, coupled to the storage medium, for executing the plurality of programming instructions. The set of communication services include services for receiving a Push-To-Talk.TM. request from the networked client computer, requesting the voice call, and in response, determining the PSTN extension. The Push-To-Talk.TM. request includes identification information of an originating web server of the Push-To-Talk.TM. option, and the determination of the PSTN extension is made in accordance with the originating web server's identification information.