3300 4.1 Choppy audio

[cmcternan]

I've been having some issues with choppy audio on a 4.1 and 4.0 ICP3300 recently.

I have seen some mention of people having similar problems on this board, but have not found any conclusive solutions.

I have been trying to troubleshoot the issue with Wireshark but do not seem to be getting anywhere. Here is a short description of my setup.

ICP3300 with PRI connection.

Phones <--> PoE Switch <--> ICP <--> PRI Adapter <--> PSTN

When calls are placed over the PRI or calls are received users are reporting that they are experiencing choppy audio. I have unfortunately been unable to duplicate this, but I have received enough reports to believe it's 'actually' happening. It appears that it is the internal handsets having the audio problems, external users seem to be getting full audio.

I have run Wireshark on the network (capturing all RTP traffic from all phones) and have seen zero packet loss or jitter.

Are there any tools I can run on the ICP itself to analyze the call quality/audio problems?

Any ideas/help is much appreciated,

Conor

 

[YnotPhone]

All the people that are experiencing these issues...
- Are they all IP sets?
- What if they call set to set (internal calls), are there problems with echo?
- Did the issues start with an upgrade or is this a new install?
- If these phones are IP, are there VLAN's splitting data and voice?
- Are all these sets on the same switch?
- Have you checked the logs to see if the system see's any issues?

 

[cmcternan]

- Are they all IP sets?
Yes

- What if they call set to set (internal calls), are there problems with echo?

No problems with internal calls.

- Did the issues start with an upgrade or is this a new install?

It's a new install. I'm actually seeing it in two locations (with slightly different network configurations). Both locations are relatively new (one from a month ago another from approx 6 months ago).

- If these phones are IP, are there VLAN's splitting data and voice?

No VLANS in use. In one location there is no other traffic on the network, while in the second location the users computers are tethered off the back of the phones. We do have QoS enabled on the PBX/Switches

- Are all these sets on the same switch?

We have multiple Linksys SRW224G4P PoE switches in the locations. Sets experiencing the problems have been on different switches.

I suspect that the issue may actually lie with the network/switch configuration, but am having a hell of a time isolating the actual cause.

All sets are connected to the switches, with each switch connecting to an 8port 100M Netgear dumb switch via a gigabit port. The PBX then connects into the switch.

This switch acts as our 'voice hub' (any voice adapters/gateways/voice services go on here).

We suspect that there might be some issues with auto-negotiation between the Managed Switches and the 'dumb' switch.

- Have you checked the logs to see if the system see's any issues?

Checking the logs on the ICP does not show us much. Nothing is standing out as being related to this. We have tried enabling the phone analyzer where the phones send data to a dedicated console. We have seen no packet loss or any issues when we run this.

 

[dryaquaman]

Just a quick check. Be sure that you don't have any data switch ports hard coded at 100meg/Full Duplex. Or if you do, be sure the other end of that patch cable is also coded to match.

Ralph

 

[IrwinMFletcher]

A couple of things to keep in mind.

Wireshark is only as good as where you sniff the packets, if you see no problems at one point, that only means that the network is good up to that point. So capture to as close to the problem (the phones in this case) as possible. Capturing directly out of the controller in this case won't show any network issues with the streaming in that direction.

If you've enabled the IPA and it doesn't indicate any problems, even for calls that people complain about, don't rule out the problem of the external lines. I've seen lots of people complain of poor audio, only to find out that they are talking to someone on a cell phone who's cutting in and out. You can disable encryption and listen to the audio captured with wireshark to see if the artifacts are pre-existing in the audio. I'd also ask the people that complain to ask the people that they are talking to when they have the problem where they are calling from, etc., just to rule that out.

 

[cmcternan]

@dryaquaman No hard coded ports on our system, although I believe we may have disabled 1000Full from our auto-neg settings on some of the ports.

"Wireshark is only as good as where you sniff the packets"

@IrwinMFletcher, yeah, I thought of that. We have the phones connecting to our PoE switches which are cascaded, the 'primary' or 'edge' switch connects to our 8port dumb switch which has the PBX on it. Any traffic from the phones either going to the controller or out onto the internet will have to pass through a specific port on this edge switch.

We mirrored this port and monitored it via Wireshark, no packet loss was detected.

Have reminded the users that cell calls can be flaky, but the sheer number of reports indicates either a real problem somewhere or a mass hallucination...

 

[LoopyLou]

Can you describe this cascading and dumb switch setup a little more? Why the 3300 not on the PoE switch?

There may be no i in team but there are three f's in fudge off.

 

[IrwinMFletcher]

So you have this config?

Phone-->POE-->POE-->POE-->SWITCH-->3300
| |
Wireshark <---- ----> Internet

Where there can be 1 or more of the POE's in line? If so, then the wireshark is not going to show you want you need to know. You need this:

Phone-->POE-->POE-->POE-->SWITCH-->3300
| |
-->Wireshark ----> Internet

With the wireshark port mirroring the phone port. The problem as you report is from the controller to the phones, so looking directly out of the controller won't show you what is happening in the rest of the network.

Or did I misunderstand your setup?

 

[YnotPhone]

Are the handsets - Wide Band on the IP phones?

If they are; can you try using some Narrow Band handsets to see if the problem still continues...

The Wideband Handsets have a known issue... this is due to a case of RevC handsets that had bad acoustic coupling.