@misc{rfc4504,
    series =    {Request for Comments},
    number =    4504,
    howpublished =  {RFC 4504},
    publisher = {RFC Editor},
    doi =       {10.17487/RFC4504},
    url =       {https://www.rfc-editor.org/info/rfc4504},
    author =    {Christian Stredicke and Steven Lass and Dr. Henry Sinnreich},
    title =     {{SIP Telephony Device Requirements and Configuration}},
    pagetotal = 37,
    year =      2006,
    month =     may,
    abstract =  {This document describes the requirements for SIP telephony devices, based on the deployment experience of large numbers of SIP phones and PC clients using different implementations in various networks. The objectives of the requirements are a well-defined set of interoperability and multi-vendor-supported core features, so as to enable similar ease of purchase, installation, and operation as found for PCs, PDAs, analog feature phones or mobile phones. We present a glossary of the most common settings and some of the more widely used values for some settings. This memo provides information for the Internet community.},
}