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Cisco Bug: CSCvt17540 - IOS XE SIP VGW is not RFC3264 compliant when receives initial SIP INVITE with 'a=sendonly'

Last Modified

Aug 29, 2020

Products (22)

  • Cisco IOS
  • Cisco ASR 1000 Series IOS XE SD-WAN
  • Cisco 4221 Integrated Services Router
  • Cisco 4321 Integrated Services Router
  • Cisco 4331 Integrated Services Router
  • Cisco VG450 Analog Voice Gateways
  • Cisco ASR 1002-X Router
  • Cisco 4431 Integrated Services Router
  • Cisco VG400 Analog Voice Gateway
  • Cisco ASR 1001-X Router
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Known Affected Releases

16.9.2 Gibraltar-16.12.1a

Description (partial)

For SIP-to-nonIP calls IOS XE voice gateway replies to initial SIP INVITE/wSDP with 'a=sendonly' with 200 OK/wSDP with no direction attribute (implying default 'a=sendrecv').
According to RFC3264 it must include 'a=recvonly' or 'a=inactive':
    If a stream is offered as sendonly, the corresponding stream MUST be
    marked as recvonly or inactive in the answer.
The issue is not present in case of SIP-to-SIP calls.
For mid-call media re-negotiations 'a=sendonly' is handled properly.

This behavior may cause one-way audio issues for certain call scenarios.

- calls from SIP to non-IP call leg, for example:
   SIP >> VGW >> PRI
- 'a=sendonly' in initial INVITE with SDP offer
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Bug Details Include

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