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Cisco Bug: CSCvh70826 - 8831 phone DTMF not getting recognized

Last Modified

Nov 08, 2019

Products (2)

  • Cisco IP Phone 8800 Series
  • Cisco Unified IP Conference Phone 8831

Known Affected Releases


Description (partial)

An issue with 8831 DTMF not getting recognized when dialed from the physical device.
When users ring conference numbers they experience issues with sending DTMF digits. 
This only happens only with Cisco 8831 phones.

Service Provider core network SBC doesn't process DTMF RTP Events if they are sent in 10ms intervals by Cisco 8831. 

8831 phone is not using ptime for rtp event that is negotiated via sdp during call establishment. Due to this some of the network devices are failing to recognize dtmf events and as a result dtmf events fail on the phone.

Phone Model - 8831/8841
Phone Firmware- sip8831.10-3-1SR3-5-EU

No additional accessories and services were configured with 8831 phone.
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Bug Details Include

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