Clicking or tapping noise on IP calls

[Jampet]

Hi all, wierd one!

I have a number of 5224's around the country all on TW.

Running an older 3300MX with Ver 8 OS.

Recently, when on a call there's a clicking or tapping noise ( like a pen tapping on a desk ) heard on the line. Sometimes it can be heard on the recipients end but not on the callers end and vice versa.

Anyone heard of this before or have any ideas?

Thanks

 

[IrwinMFletcher]

Packet loss can sound like a clicking noise.

 

[MitelInMyBlood]

Visualware dot com over on the left side of their home page under free products & services has a link to a free VOIP quality test. It's a 15-day trial but fully functional.

If this problem is isolated to only one or two of your TW users you might check to see if they're plugged into a hub instead of direct in to the router or etherswitch. Hubs and VOIP don't live together happily.

Original MUG/NAMU Charter Member

 

[Jampet]

Thanks for the advice, I'll take a look.

 

[slapin]

This clicks have regilar intervals or random. Packet loss has random pattern and codec adds "metalic" voice trying to compansate single lost packets. Is it a pure IP call? No IP/TDM crossings?

 

[Jampet]

Generally, they are random. It does'nt seem to happen IP to IP only IP to TDM or non IP destinations.

 

[slapin]

What kind of external lines or TDM destinations do you use?

Internal analog phones.
External analog trunks
External digital/isdn trunks?

Do you experience something like this when calling from internal IP phones?

Do you have compression transcoding on TW server?

Can you enable voice quality monitoring on ICP and see if you have any packet loss or excessive jitter or any other metricas out of normal range.

Do you have enough DSP resources or any alarms related to DSP?

Check TW server logs. At the end of each call it does report total packet loss.

These are areas which can contribute to the issue.

We use TW and once in a while I observe massive packet loss from some of the users while others are just fine. You cannot effectively control this and users have to be aware of this technology limitations.

 

[Jampet]

I'm seeing Minor alarms on TW stating " excessive jitter" and it seems to be the same handsets everytime.

They're all on TW. Could it be an issue there end?

 

[Jampet]

Also, would G.729 transcoding enabled help this?

 

[Jampet]

Sorry slapin, to answer your questions.


Internal analog phones. - NO
External analog trunks - NO
External digital/isdn trunks? - NO

Do you experience something like this when calling from internal IP phones? - NO

Do you have compression transcoding on TW server? NOT ENABLED

Can you enable voice quality monitoring on ICP and see if you have any packet loss or excessive jitter or any other metricas out of normal range. - Seeing both pkt loss and jitter.

Do you have enough DSP resources or any alarms related to DSP? DSP?

Check TW server logs. At the end of each call it does report total packet loss. which log is it?

These are areas which can contribute to the issue.

We use TW and once in a while I observe massive packet loss from some of the users while others are just fine. You cannot effectively control this and users have to be aware of this technology limitations. That's what I tell them!

 

[slapin]

Packet loss up to 1% is OK jitter under 200 ms is also ok. In voice quality stats buffer underruns and overruns should be 0 or some insignificant number.

DSP - digital signal processor. You can check it by entering a maintenance command SHOW STATUS DSP (I don't remember if it is available in V.8)

Transcoding on TW will require additional license and put more load on the server. I prefer using pass-through mode (master). So move your TW users into different compression zone and enable intrazone compression on the controller. This way all calls will be set with G.729 codec when possible. It can save some bandwidth. G.729 will require about 36kbps compared to about 80kbps for G.711 including all overheads. Also you need to make sure that you allocate enough bandwidth for your TW server itself on your Internet connection, so users downloading fresh funny video or M$ updates will not affect voice conversations.