On Sun, Jun 17, 2012 at 6:44 AM, Steve Underwood <steveu@coppice.org> wrote:
I thought the only Cisco products which did this were the ones which started as Linksys/Sipura products. The usual G.729 problem with real Cisco products is G.729 with the bits packed in the opposite order to the RFC. This isn't an error. Cisco implemented G.729 in RTP before there was a standard, and the packing order they chose just happened to be the opposite of the standard. Of course, modern Cisco kit implements the standard order, but they can still do the opposite order for backwards compatibility with their own kit. Sometimes you still meet systems configured to use that, and G.729 calls produce a horrible noise.
You are generally correct, however, some of the rtmpap G729a craziness seems to have moved to "Cisco proper". I've seen IOS-powered media gateways and CallManager express systems put G729a in the rtpmap. With how much that hardware interacts with the current line of rebadged Sipura/Linksys phones I can't say I'm completely surprised. -- Kristian Kielhofner