1. A method comprising: receiving, by a call broker, via a data connection, a request from a first participant requesting establishment of a voice call, wherein the request comprises a callback number of the first participant and account information; receiving, by the call broker, validation of the account information; sending, by the call broker, voice call session information and an authorization code to the first participant in response to the request; receiving, by the call broker, from a second participant requesting participation in the voice call, a callback number of the second participant, the voice call session information and the authorization code, wherein the first participant and the second participant are engaged in a chat session and wherein the first participant passed the voice call session information and the authorization code as a private message in the chat session to the second participant; establishing, by the call broker, a first voice link to the first participant using the callback number of the first participant; determining, by the call broker, an internet protocol address associated with the second participant using the callback number of the second participant when a public switched telephone network link of the second participant is unavailable due to the public switched telephone network link of the second participant being in use in an internet session through a respective internet service provider access server; establishing, by the call broker, a second voice link, via a voice over internet protocol gateway, to the second participant using the internet protocol address associated with the second participant; and bridging, by the call broker, the first voice link and the second voice link so as to establish the voice call between the first chat participant and the second chat participant.