%% You should probably cite draft-ietf-sipping-session-policy-framework instead of this I-D.
@techreport{hilt-sipping-session-policy-framework-01,
    number =    {draft-hilt-sipping-session-policy-framework-01},
    type =      {Internet-Draft},
    institution =   {Internet Engineering Task Force},
    publisher = {Internet Engineering Task Force},
    note =      {Work in Progress},
    url =       {https://datatracker.ietf.org/doc/draft-hilt-sipping-session-policy-framework/01/},
    author =    {Volker Hilt},
    title =     {{A Framework for Session Initiation Protocol (SIP) Session Policies}},
    pagetotal = 28,
    year =      2006,
    month =     mar,
    day =       7,
    abstract =  {Proxy servers play a central role as an intermediary in the Session Initiation Protocol (SIP) as they define and impact policies on call routing, rendezvous, and other call features. However, there is currently no standard mechanism by which a proxy can influence session policies such as the codecs or media types to be used. This document specifies a framework for SIP session policies. It defines two types of session policies, session-specific and session- independent policies and introduces a model, an overall architecture and the protocol components needed for session policies.},
}