Crackling/Static on Phones

[Engineer1017]

Hello Community,

I have been beating my head against a wall here since last year looking into an issue with a 3CX deployment. I have decided to open this up to the community at large to try and brainstorm some ideas.

This deployment is on-prem and is using Spectrum as the SIP provider through their voice gateway device.

The phones are Yealink T33G running firmware 124.86.0.40 and unsupported firmware 124.86.0.113.
The issue happens regardless of firmware version.

Before you ask, we are using the unsupported firmware because of the need for enabling wireless headsets on the T33G phones and only on the phones that have a heaset attached to them.

Phones are powered through POE from two Unifi USW 48 PoE switches.
Phones provisioning method is local as they are on the same subnet as the 3CX system.


Issue: Crackling/Static on random phones at random times and can be heard when the phone rings and during calls using either the handset or headsets. Users on the other end of the call do not hear the noise either. Only the person at the physical phone hears the crackling and static.

Troubleshooting steps taken:
1. Call recordings - The static and crackling sounds are not heard in the recording
2. Rebooting phone - Issue goes away but comes back randomly and not always the same phone.
3. Initial PBX box ran Windows 11 Pro with 3CX V18 installed on it. Swapped to secondary PBX box which ran Windows Server 2022 with 3CX V18 on it. (Latest updates installed)
4. Turned POE off on one switch port and added a power adapter to one phone - (Still waiting to see if the crackling/static comes back to this phone)
5. Ran packet captures and even had 3CX support look at the audio and packet capture but they did not see any problems.
6. Migrated all phones and phone system along with spectrum SIP gateway to dedicated VLAN off of the main company network.

Yealink Support has been contacted and they have provided us with a newer firmware to try which is 124.86.0.156 but we have not tried it yet until we get confirmation the headsets are still enabled on this firmware.

The fact that the crackling/static happens even when the phone is just ringing, makes me think the issue is with the phones themselves.
Just to include the only software we have running on the 3CX box outside of 3CX is our remote tools which allow us remote access to the system.

 

[VoIPTools]

When I first read the title of this post I thought the answer would be straightforward. I assumed the problem was related to analog since digital communication does not experience crackling or static EVER. Take that to the bank. Like you, I would have asked the following questions:

• Do you employ any analog (POTS) lines in your 3CX infrastructure?
• Does your caller use analog?
• Does the crackling / static show up in the wire capture?
• Who hears noise?

Your first clue is that the outside party does not hear the noise. Your second clue is that only the Yealink user hears the noise. Your 3rd clue is that the noise is not captured by the wire capture. You now have your answer.

Since digital conversations will NEVER have static or crackling, and the wire capture does record the noise from either side of the conversation, there is only one explanation -- it must be either the handset or more likely the headset.

If you do not use the headset, do you still experience the noise? If you do, then swap out one of the phones experiencing the problem with a different model, and without a headset. My bet is on the headset.

 

[Engineer1017]

• Do you employ any analog (POTS) lines in your 3CX infrastructure? - No
• Does your caller use analog? - Do not know as its not tied to a specific caller.
• Does the crackling / static show up in the wire capture? - No as according to 3CX support, the packet captures look fine as they could not find anything wrong with them.
• Who hears noise? - Only the person on the Yealink phone hears the noise.

If you do not use the headset, do you still experience the noise? - The noise can be heard from both the handset and the headset so it does not matter which one they use.

If you do, then swap out one of the phones experiencing the problem with a different model, and without a headset. My bet is on the headset. - I am hesitant to call this a headset or handset issue as the issue moves around to phones at random. As soon as we power cycle the handset the problem goes away for that phone for a while until it comes back. Swapping the phones does not help either as it's not always the same phone having the problem.

Yealink support responded this morning and confirmed that the updated firmware does still enable headset functionality, so I am planning tonight to upgrade all of the phones to the firmware they recommended to see if that makes a difference.

 

[SweetAction]

Are your phone powered by POE or power adapter?

 

[Engineer1017]

Are your phone powered by POE or power adapter?

POE, except for one that we moved over to a power adapter late last week.

 

[SweetAction]

POE, except for one that we moved over to a power adapter late last week.

I totally missed that you were already looking at the power. Disregard me and carry on.

 

[VoIPTools]

How about this -- are they wireless headsets? Maybe something periodically interferers with the communication between the headset and the base station/dongle? My money is still on the headset.

But could you clarify your statement -- you hear the noise even when the headset is completely removed from the phone? Or do you hear it through the handset only when the headset is connected to the phone. That would be my next test.

 

[CentrexJ]

We have sold hundreds of the T33G phone. Occasionally you will have to restart/reboot the phone and the issue goes away. It doesn't happen often but it does happen. The higher end T4 and T5's don't have this issue.

 

[Engineer1017]

It's not the headsets as the issue happens as well on the phones that do not have the headsets.

 

[CentrexJ]

It's not the headsets as the issue happens as well on the phones that do not have the headsets.

Try restarting a phone, fixes the issue for my clients and none have headsets on T33G

 

[NicholasP_3CX]

Also, if it is isolated one one phone, check the curly cable. Check with the speakerphone if the problem persists.

Also, is that user using one of those swivel things that prevents the tangling of the cable? Those sometimes also cause audio crackling.

 

[VoIPTools]

I think we are all in agreement. It's not likely an issue with the PBX, the network, or the SIP trunks. If it happens on phones that don't use a headset, then it has to be the phone. I had my money on the headset, and I'm super surprised to hear it might be the phones.

 

[Engineer1017]

I think we are all in agreement. It's not likely an issue with the PBX, the network, or the SIP trunks. If it happens on phones that don't use a headset, then it has to be the phone. I had my money on the headset, and I'm super surprised to hear it might be the phones.

I completed the firmware updates as recommended by Yealink so at this point it's wait and again. I'll post if anything happens or doesn't happen.

 

[paulengelen]

I completed the firmware updates as recommended by Yealink so at this point it's wait and again. I'll post if anything happens or doesn't happen.

What firmware are you running on now? We have the same issue with the T33P. Is it solved for you?. If so, could you send me the firmware?

 

[Engineer1017]

What firmware are you running on now? We have the same issue with the T33P. Is it solved for you?. If so, could you send me the firmware?

Hi,

Yes the newer firmware actually did fix the issue for us. I apologize for not coming back to update this forum thread as I have been tied up on other projects.

I am happy to share the firmware with you if it might help you. The version they provided me was 124.86.0.156. PM me your email and I'll send it over to you.

 

[Ibby-WaveLengths]

Hi all, I have a similar post titled:

Yealink T33G Random Audio Issues​

Are you able to share a link to the firmware for us to try and use?

Other guys on this forum have tested the firmware and have advised that 124.86.0.156 appears to be working and the issues have not yet recurred. but 3CX will not confirm on the results of their testing of the said version of firmware from Yealink (this was when we asked them in January 2024 already).

Help will really be appreciated.