Solved Incoming Audio Pausing during call

[Printcnx]

Recently Upgraded to V15.5 and during external calls incoming audio pauses for a couple seconds in the middle of a call. 3cx dashboard is not showing any errors.

We are using Htek UC924 Phones and had no issues whatsoever on the previous version of 3cx.

 

[leejor]

Only on incoming calls, not on outgoing? External, or internal calls as well?
What type of trunking are you using?
Does it happen about the same point in time during the call?
Does it happen one way, or both?
Any Codec changes made?

 

[Printcnx]

Hi Leejor,

It seems to be an issue only on calls that leave the office incoming & outgoing.

The external caller is not aware of the audio drop so it looks like it is one sided on our end.

This also happens with external extensions where our remote staff calling into the office have the audio drop for a couple seconds. When this happens its been notice in both directions.

So far we have not been able to pinpoint an exact time when the issue happens during the call. I has however happens a couple of times during the same call. We will keep an eye on it to see if its a specific time during calls.

We've been running ping tests to see if maybe its a packet loss issue and our connection (fiber) seems to be fine no packet loss.

External connections are on Cable however nothing seems wrong with those connections other than the normal jitter.

Sip Trunks are provided by Vitelity and nothing has been flagged on that end as of yet.

Our phones are running the recommended firmware however the 3cx dashboard is stating that.
"You are using Unsupported phones or phones with custom templates which may cause issues."

Htek phones have had no firmware changes since the previous version of 3cx.
Running: 2.0.4.4.31

Tried changing the audio codex to favor G279A/B from the default as well as checked PBX to deliver audio and still having the same issue.

We also did a clean install of the linux distro of 3cx and restored a backup last night and are still having the same issues today. : (

 

[leejor]

When did this start? Has it been this way from "day one", or was there a change?
It may be "something" in your network. You could try eliminating/substituting various devices, to see if that makes a difference. Since it seem to affect remote extensions (but not local) as well as trunk calls, it would appear to be something to do with your ISP connection.

 

[Printcnx]

Hi Leejor,

This only started after updating to the latest version of 3cx (V15.5.). We've been using 3cx for several years no with minimal issues and nothing persistent such as this audio issue.

We will keep troubleshooting but may ultimately end up rolling back to a previous version of 3cx to see if that corrects the problem.

 

[Gav]

I seem to be having the same issue, although the audio drop out occurs at the start of the call.
It's been working fine for ages...this problem has started over the past few weeks.

 

[Printcnx]

Have some updates and made tons of adjustments and still having the same issue.

Changed our system to a Google hosted 3cx server. Not ideal as we already had a dedicated machine at our office but after numerous attempts to get this audio issue resolved we thought it would be worth a shot.

We have done the following in attempts to resolve the intermittent audio drop on calls.

1. Changed SIP Trunk Provider from Vitelity to Flowroute (thinking a closer geographic hop would help our cause)

2. Implemented various firewall rules on or firewall to see if alternative setups or NAT translations would help. (using Sophos UTM 9)

3. We've now re-installed 3cx from scratch on a google VM using PBX Express. Static IP, Everything on the 3cx firewall checker looks good.

4. Phones at our location are now connecting via the 3cx SBC run on a dedicated Debian 9 machine.

5. Remote location phones are connected via stun.

6. All phones have had their firmware factory restored and phone have been freshly provisioned by 3cx server. (All HTEK UC924 Phone)

After all of these changes we've had a slight improvement in audio quality, but the random audio drops are still happening. Typically starts after a couple of minutes, audio drops for 5 seconds or so and then call resumes as normal.

We have a fiber connection coming into our office with a dedicated IP and have a symmetrical connection of 1000/1000.

Short of putting in a new firewall we're at a loss for ideas to try.

 

[YiannisH_3CX]

Hello @Printcnx

I think the next step is to try to rule out the firewall. Since this is a hosted server try to move an extension outside of the office and see if you are still facing the issue.
You can use an SBC to provision a phone or STUN. You can even try a 3CX client for Android or iOS and use 3G/4G to bypass the firewall. See if you can replicate the issue when calling external numbers.
You could also try having a few users in the office switch to 3CX clients and see if they can replicate the issue internally.

 

[Printcnx]

Hi YiannisH,

So remote users using stun are having the audio issue as well.
Both are on residential cable connections (Comcast Xfinity) 150mbs down 10mbs up.
I don't believe it is a connection issue as when audio is working it sounds great.
still getting intermittent audio cutting out for 3-5 seconds during calls.

We experienced this during a company conference call with an outside vendor today multiple times during the call.

I think at this point I can factor out the firewall as a possible cause to the audio issue.

I've told our staff that have 3cx desktop client to use that as a primary if possible but we have many users that prefer a desk phone.

is it possible the Htek phones / firmware are not 100% compatible with the current version of 3cx? We are using Htek UC924 Phones. Would changing the primary audio codex help?

 

[YiannisH_3CX]

I've told our staff that have 3cx desktop client to use that as a primary if possible but we have many users that prefer a desk phone.

So the 3CX client users do not face this issue?

is it possible the Htek phones / firmware are not 100% compatible with the current version of 3cx? We are using Htek UC924 Phones. Would changing the primary audio codex help?

We haven't had any other reports regarding this issue so i would not think that it is a firmware issue.
You can try changing the codecs and see if that helps but if the codecs were the issue then you would experience bad quality or no audio at all.

Try the echo extension test. Call *777 and keep talking for a few minutes and see if you can replicate the issue. This way you can factor out the provider as well. If the issue persists then the only way to see what the issue is by using wireshark and capturing the issue.

 

[Two-iT]

Same here,
4 Customers facing the same problem.
Dutch VoIP Provider
Cisco IP 7900 series
Panasonic KXHDV series
PBX local

It's like someone is pushing a button during the call what results in phonecalls that are interuppted during words.

 

[Printcnx]

So finally have a resolution to this issue.

After switching servers, firewall, sip connection just about every avenue to no avail.

3cx released an updated firmware for the HTEK phones and everything is now working as it should.

This seems to have been 100% a firmware issue.

 

[YiannisH_3CX]

So finally have a resolution to this issue.

After switching servers, firewall, sip connection just about every avenue to no avail.

3cx released an updated firmware for the HTEK phones and everything is now working as it should.

This seems to have been 100% a firmware issue.

Glad to see the issue has been resolved and thank for updating the thread with your solution.