A voice-over-Internet-Protocol (VoIP) client codes audio data as printable ASCII characters, then embeds the ASCII audio data inside a cookie that is sent over the Internet within an HTTP GET message. The GET message is sent to a server acting as a call proxy or external manager that forwards the audio data to a remote client. Return audio data is sent back to the client in the normal data field of an HTTP response message from the server. When the client receives the HTTP response, it sends another GET message without audio data, allowing the server to send another response. This empty GET allows VoIP to pass through strict firewalls that pair each HTTP response with a GET. For secure-sockets layer (SSL), client and server exchange pseudo-keys in hello and finished messages that establish the SSL session. Audio data is streamed in SSL messages instead of encrypted data.
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