Duplicate c= Lines in SDP Cause Intermittent One-way Audio with Various ITSP(s)

Publisher

Cisco Systems

URL

https://www.cisco.com/c/en/us/support/docs/voice-unified-communications/unified-border-element/116010-dup-c-lines-problem-solution-00.html

Published

2013-04-26

Updated

unknown

Accessed

2026-09-24

HTTP status

200

License

Cisco copyright; no-redistribution; short excerpts and locators only

Source notes citing this source

• Cisco documents intermittent one-way audio with some ITSPs whose equipment does not accept SDP carrying both a session-level and a media-level c= line, although the SDP specification permits it. in context
• Cisco's workaround for the duplicate c= line problem is a voice class SIP profile that removes the Audio-Connection-Info SDP header from REINVITE requests and 200 responses, applied globally or per dial-peer. in context

Cite this source record

APA

WarmTransfer. (2013, April 26). Duplicate c= Lines in SDP Cause Intermittent One-way Audio with Various ITSP(s). WarmTransfer. https://warmtransfer.net/knowledge/sources/cisco-technote-116010-cube-dup-c-lines

BibTeX

@misc{warmtransfer-cisco-technote-116010-cube-dup-c-lines,
  title  = {Duplicate c= Lines in SDP Cause Intermittent One-way Audio with Various ITSP(s)},
  author = {{WarmTransfer}},
  year   = {2013},
  url    = {https://warmtransfer.net/knowledge/sources/cisco-technote-116010-cube-dup-c-lines},
  note   = {Cisco Systems, accessed 2026-09-24}
}