{"draft":"draft-worley-alert-info-fsm-10","doc_id":"RFC8433","title":"A Simpler Method for Resolving Alert-Info URNs","authors":["D. Worley"],"format":["ASCII","HTML"],"page_count":"45","pub_status":"INFORMATIONAL","status":"INFORMATIONAL","source":"INDEPENDENT","abstract":"The \"alert\" namespace of Uniform Resource Names (URNs) can be used in\r\nthe Alert-Info header field of Session Initiation Protocol (SIP)\r\nrequests and responses to inform a voice over IP (VoIP) telephone\r\n(user agent) of the characteristics of the call that the user agent\r\nhas originated or terminated.  The user agent must resolve the URNs\r\ninto a signal; that is, it must select the best available signal to\r\npresent to its user to indicate the characteristics of the call.\r\n\r\nRFC 7462 describes a non-normative algorithm for signal selection.\r\nThis document describes a more efficient alternative algorithm: a\r\nuser agent's designer can, based on the user agent's signals and\r\ntheir meanings, construct a finite state machine (FSM) to process the\r\nURNs to select a signal in a way that obeys the restrictions given in\r\nthe definition of the \"alert\" URN namespace.","pub_date":"August 2018","keywords":["Alert-Info","audio signals","call signaling","call transfer","resolution","signaling","signals","SIP","URN","visual signals"],"obsoletes":[],"obsoleted_by":[],"updates":[],"updated_by":[],"see_also":[],"doi":"10.17487\/RFC8433","errata_url":null}