\begin{thebibliography}{10}

\bibitem{rfc2543}
M.~Handley, H.~Schulzrinne, E.~Schooler, and J.~Rosenberg, ``{SIP:} session
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\bibitem{rfc3050}
J.~Lennox, H.~Schulzrinne, and J.~Rosenberg, ``Common gateway interface for
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\bibitem{draft-ietf-iptel-cpl}
J.~Lennox and H.~Schulzrinne, ``{CPL:} a language for user control of internet
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\newblock Work in progress.

\bibitem{draft-ietf-sip-call-flows}
A.~Johnston, S.~Donovan, R.~Sparks, C.~Cunningham, D.~Willis, J.~Rosenberg,
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\newblock Work in progress.

\bibitem{rfc2327}
M.~Handley and V.~Jacobson, ``{SDP:} session description protocol,'' Request
  for Comments 2327, Internet Engineering Task Force, Apr. 1998.

\bibitem{E.721}
{International Telecommunication Union}, ``Network grade of service parameters
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\bibitem{Bell91:Digital}
J.~Bellamy, {\em Digital Telephony}.
\newblock New York: John Wiley \& Sons, 1991.

\bibitem{Schm9904:Analytical}
F.~Schmidt, F.~G. López, K.~Hackbarth, and A.~Cuadra, ``An analytical cost
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\bibitem{FCC0012:Trends}
{Common Carrier Bureau}, ``Trends in telephone service,'' tech. rep., Federal
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\bibitem{Duff7801:Study}
F.~P. Duffy and R.~A. Mercer, ``A study of network performance and customer
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\end{thebibliography}
