@techreport{rfc-3261,
  author = {Jonathan Rosenberg and Henning Schulzrinne and Gonzalo
 Camarillo and Alan Johnston and Jon Peterson and Robert Sparks and Mark Handley and Eve Schooler},
  title = {{SIP}: {S}ession {I}nitiation {P}rotocol},
  type = {RFC},
  institution = {IETF},
  number = {3261},
  month = {June},
  year = {2002}
}