[VoiceOps] ATA CPE and RFC2833

Alex Balashov abalashov at evaristesys.com
Thu Feb 16 03:22:14 EST 2012

Ah.  Well, then it's pretty definitively a buggy ATA.  :-)

On 02/16/2012 03:16 AM, Peter Childs wrote:

> In a isolated environment I plugged one of our lab switching nodes (ip->tdm) into a loopback device on the other side to 'loop' back audio.
> Using a soft-client that only sends rfc2833 (rtp.p_type==101) I can 'see' the DTMF digits in both directions (and hear them fed back via the loopback), however in Wireshark (1.4.2 on MacOSX) they generate no visible or audible artefacts in the RTP stream playback (they are visible in the capture, and the 'flow diagram').
> Then using my suspect ATA I see rtp.p_type==101 digits again (and confirmed by 'debug voip rtp named-event') however in my wireshark RTP stream I can 'see' audio and 'hear' it as well as seeing the nte events.
> I also just created a 'display filter' in wireshark 'rtp.p_type != 101 || mgcp' to show only the MGCP and RTP (without named events) and then saved a copy of only displayed packets.   Loading this capture (the filtered capture) and decoding the voice playback shows audio tones in packet.

Alex Balashov - Principal
Evariste Systems LLC
260 Peachtree Street NW
Suite 2200
Atlanta, GA 30303
Tel: +1-678-954-0670
Fax: +1-404-961-1892
Web: http://www.evaristesys.com/, http://www.alexbalashov.com/

More information about the VoiceOps mailing list