RFC 3960: Early Media and Ringing Tone Generation in the Session Initiation Protocol (SIP)

Publisher

IETF / RFC Editor

URL

https://www.rfc-editor.org/rfc/rfc3960.html

Published

2004-12-01

Updated

unknown

Accessed

2026-09-24

HTTP status

200

License

IETF Trust legal provisions; RFC text may be reproduced with attribution; short excerpts and locators only

Source notes citing this source

• RFC 3960 states that a 180 (Ringing) response means the callee is being alerted, and a UAS should send it when the callee is being alerted regardless of the status of the early media session. in context
• Per RFC 3960, the Alert-Info header tells the UAC which tone to play if it generates local ringing, but not when to generate local ringing. in context
• RFC 3960's application server model uses a separate offer/answer exchange for early media, carried as early-session bodies, so a UAC can reject or mute early media offers without muting the regular session. in context
• RFC 3960 warns that media clipping is likely when a muted early dialog becomes the answered dialog, because the UAC sends an UPDATE with a new offer and the UAS cannot send media until it receives that offer. in context
• Per RFC 3960, when a UAC receives early media from several UASs after forking it typically picks one early dialog at random and mutes the rest. in context
• In RFC 3960's gateway model, early media sessions are managed with offer/answer exchanges carried in reliable provisional responses, PRACKs and UPDATEs. in context
• RFC 3960 states that the gateway model does not work well with forking. in context
• Under the RFC 3960 policy, if a 180 (Ringing) has been received but no incoming media packets are arriving, the UA generates local ringing. in context
• Under the RFC 3960 policy, if a 180 (Ringing) has been received and incoming media packets are arriving, the UA plays them and does not generate local ringing, stopping any local ringing already under way. in context
• RFC 3960's recommended policy for a POTS-like SIP UA is to never generate local ringing unless a 180 (Ringing) response has been received. in context
• RFC 3960 gives ringing tone and announcements such as queuing status as typical examples of early media generated by the callee. in context
• RFC 3960 (Early Media and Ringing Tone Generation in SIP) was published in December 2004 with category Informational. in context
• RFC 3960's ringing-tone policy is keyed on 180 (Ringing) and incoming media; the fetched text did not show it assigning any role to 183 (Session Progress). inferred in context
• RFC 3960's security considerations say UAs should encrypt session descriptions (for example with S/MIME) and use media-level authentication such as SRTP, because attackers may send packets to the transport address in an early session description. in context

Cite this source record

APA

WarmTransfer. (2004, December 1). RFC 3960: Early Media and Ringing Tone Generation in the Session Initiation Protocol (SIP). WarmTransfer. https://warmtransfer.net/knowledge/sources/rfc-3960-early-media-ringing

BibTeX

@misc{warmtransfer-rfc-3960-early-media-ringing,
  title  = {RFC 3960: Early Media and Ringing Tone Generation in the Session Initiation Protocol (SIP)},
  author = {{WarmTransfer}},
  year   = {2004},
  url    = {https://warmtransfer.net/knowledge/sources/rfc-3960-early-media-ringing},
  note   = {IETF / RFC Editor, accessed 2026-09-24}
}