| 摘要 |
In providing an information assistance service, information assistance calls are routed through a telephone carrier switch to information/call centers for handling the calls. For each call, the carrier switch establishes a Voice over Internal protocol (VoIP) call session, and conducts handshaking with a redirect server in an information assistance system, e.g., in accordance with a session initiation protocol (SIP). In response to an Invite message to the redirect server, the redirect server provides a list of available call centers in a Multiple Choices response message to the carrier switch. The latter negotiates with ones of the call centers on the list to set up the VoIP call session.
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