Polycom KIRK DECT & CME - voice quality

[edwardforgacs]

I have recently tried to set up a Polycom KIRK DECT solution with Cisco CME. The Polycom KIRK Wireless Server 600v3 is on the officially supported list from Polycom using the SCCP for older versions of Cisco CME, but not 8 or 8.5 which I tested it with.

The KIRK 2010 phones register successfully with CME and are able to make and receive calls. The problem, however, is that the sound quality is atrocious. The other party is virtually unable to hear due to the volume being so soft, and the far-end party can also hear very noticeable echo and distortion. The sound on the actual Polycom handsets is slightly muffled and lacking in clarity, but nowhere near as bad - no distortion really. So, it seems OK on the Polycom, but not on the far end.

As the KIRK handsets integrate via SCCP and emulate a Cisco 7940, we had hoped this solution would just plug in and work, unfortunately it really does not.

Can anyone suggest how to troubleshoot the voice issues in this sort of environment? I would like to clarify that the voice issues are 100% isolated to the Polycom. We do have the obvious things like QoS properly set up on the network and the Cisco 7962/7965 IP phones have no voice quality issues. We’re really at the point that there just don’t seem to be any configuration settings to change, as it is so simple on both the CME and Polycom ends, there isn’t really even a volume or gain setting for SCCP extensions.

I must say it has crossed my mind that being the base model, the KIRK 2010 handset is probably not the best quality. I just find it to believe that Polycom would produce a handset where this voice quality is that bad. To give an idea, it really is far worse than any other digital cordless phone I have used. Does anyone have experience with this or another KIRK handset, and could comment on the overall voice quality?

On a side note, there have been a few old posts around this forum regarding setting up the Polycom KIRK unit with CME, and the difficulties of this. If anyone needs assistance with getting the phones to register to CME, I am happy to explain how to do it. In general though, I would really think twice about using the Polycom KIRK solution with Cisco, especially on CME, as it involved an incredible amount of hassle with different departments and partners of Polycom as virtually no-one knew anything about the SCCP firmware and licensing, and the documentation was very poor and incomplete.

[paolo bevilacqua]

To begin with, if you press ? twice on the Cisco 796x, are there any packet loss reported ?

Any chance that the problem is limited to a faulty handset ?

If you load SIP firmware (I am just assuming that is an option), does the voice quality improves ?

Another troubleshooting step could be to span voice vlan to a wireshark port, and check if there is any anomaly in the RTP stream. You can also listen to it actually.

Regarding your note about this integration. It's kind of know in the industry that after an initial collaboration, Cisco and Polycom took different routes on not so good terms some years ago. Maybe that partially explains why none of the parties makes a strong effort to interwork now.

[un]

What Codec do you use and what is the framesize on your config ?

Please see the attached doc with a screendump of my config.

We have more that 200 Kirk DECT 600v3 antennas running in our Cisco enviromnent, and it works

[edwardforgacs]

Thanks for the suggestions. Pressing ? twice on the Cisco 79xx phones on internal calls and specifically a call between the Cisco and Polycom handset does not report any packet loss. There is "Rcvr Discarded: 1" on every call, "Rcvr Lost Packets: 0". Jitter varies between about 5-10, on internal calls the Avg MOS LQK is consistently 4.5000, conceal seconds consistently zero.

I did test it also on some calls to an external extension without proper QoS to see if the stats were actually correct, and they showed some minor packet loss, not really to the point of impacting voice quality noticeably. I can't stress enough that I really don't think there is any packet loss inside our network, I am convinced this is an audio/codec/DSP processing issue, or some sort of hardware bug.

To clarify also I have also tested with two separate Polycom 2010 handsets, and the audio quality for the remote party was shocking on both.

I have not yet been able to try recording via Wireshark but I will definately do that. I have also not tried SIP firmware but if a third-party SIP phone is used by the remote party (not the Polycom), the problem is still there.

The codec being used is G.711u, I also tried G.711a which didn't make any difference. I matched the frame size settings to the config you suggested. They were slightly out, and changing them all down to 20ms resulted in a slight improvement in the quality - the length of the echo was reduced, but still noticeable, and nowhere near good enough.

Can I ask which handset you are using in your 200 phone Polycom deployment?

[un]

We are actually using Siemens DECT phones, because the quality of the Kirk phon

es was not very good.

[edwardforgacs]

I assume you mean the Siemens gigaset series?

So when you say the quality was "not very good", was it the same problem I am having with distortion/echo, or something else?

Also, I don't suppose you know if the Aastra DECT phones are compatible with the Polycom KIRK server? I was tempted to try one of those...

[edwardforgacs]

Would you mind at least telling me which models of Kirk handset you tried and found to not have very good audio quality?