Preview Tool

Cisco Bug: CSCtb66341 - MGCP Mid Call payload changes result no audio for static/dynamic codec

Last Modified

Jan 31, 2017

Products (33)

  • Cisco 2800 Series Integrated Services Routers
  • Cisco AS5400XM Universal Gateway
  • Cisco 888W Integrated Services Router
  • Cisco 861W Integrated Services Router
  • Cisco 892W Integrated Services Router
  • Cisco 3845 NOVPN Integrated Services Router
  • Cisco AS5350XM Universal Gateway
  • Cisco 881W Integrated Services Router
  • Cisco 861 Integrated Services Router
  • Cisco 888 Integrated Services Router
View all products in Bug Search Tool Login Required

Known Affected Releases

12.4(22)YB2 12.4(23b)

Description (partial)

Symptoms: MGCP Mid Call payload changes result in no audio for static/dynamic 


1. When a MGCP call is using a static codec and then a MDCX is received with 
LCO having a dynamic codec (say G-723H) but without an SDP. In this scenario, 
a dynamic payload is not reserved for the new codec, and the call continues to 
use the old payload type for the new dynamic codec resulting in no audio.

2. When a MGCP call is using a dynamic payload type (say 99) for a codec (say 
G729B) and then a MDCX is received for the same codec but with a static payload 
type(18). In this scenario, since there is no codec change the call continues 
to use the payload type 99 in RTP stream. This should be changed to use the 
negotiated payload type 18.
Bug details contain sensitive information and therefore require a account to be viewed.

Bug Details Include

  • Full Description (including symptoms, conditions and workarounds)
  • Status
  • Severity
  • Known Fixed Releases
  • Related Community Discussions
  • Number of Related Support Cases
Bug information is viewable for customers and partners who have a service contract. Registered users can view up to 200 bugs per month without a service contract.