%% You should probably cite draft-ietf-sipping-policy-package instead of this I-D.
@techreport{hilt-sipping-policy-package-01,
    number =    {draft-hilt-sipping-policy-package-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-policy-package/01/},
    author =    {Volker Hilt and Gonzalo Camarillo},
    title =     {{A Session Initiation Protocol (SIP) Event Package for Session-Specific Session Policies.}},
    pagetotal = 14,
    year =      2006,
    month =     mar,
    day =       8,
    abstract =  {This specification defines a Session Initiation Protocol (SIP) event package for session-specific session policies. This event package enables users to subscribe to the policies for a SIP session and to receive notifications if the policies change. The package is part of the Framework for SIP Session Policies.},
}