Hello,

Apologies for the late reply.

I don’t think there’s any transcoding, as the endpoint negotiation is set to “generous” and examining the SDPs shows that both endpoints negotiate on PCMA/PCMU. I got a pcap of the RTP streams with tcpdump and I see that from the 126500 packets, 62964 are marked with “bad udp cksum”. All packets with bad udp checksum are originating from the FreeSWITCH box. Is this information helpful at all and what else can I do to figure out the reason behind these issues? Thank you!

Kind regards,

--

Iskren Hadzhinedev

On Tuesday 14 October 2014 10:03:32 Michael Jerris wrote:

is there even any transcoding involved in your scenario?  Are the artifacts present in the inbound stream as well.  I would get a tcpdump and analyze the inbound and outbound streams to see a bit more detail of what is going on.

Mike

On Oct 14, 2014, at 5:12 AM, Iskren Hadzhinedev <iskren.hadzhinedev@ikiji.com> wrote:

Hi everyone,

Some of the calls using PCMA/PCMU have artifacts (distorted sound, “robotic” voice, stutter) on what looks like a random basis. The other codecs I have tried don’t have issues (tried GSM, iLBC,G722, G729, SILK). Apart from FreeSWITCH, the only other thing running on the machine is a static webpage served by nginx and the load is almost always at 0. Any help or advise on how to chase down this issue is highly appreciated!

System specs:

Machine: Xen VM

RAM: 1GB

CPU: Dualcore 2.4 Ghz 64bit

OS: CentOS 6.5

FreeSWITCH Version: 1.5.13b+git~20140621T003222Z~47891d5caa~64bit

Max # simultaneous calls: 12

Calls per second: at most 3

Endpoints used for testing:

Hardware phones: Yealink T42G, Yealink T48G, Gigaset DE900, Cisco 7975 (with SIP firmware)

Softphones: CounterPath Bria for Android, CsipSimple (android), Linphone, Jitsi

Mobile provider and a landline via gateway.