Call Quality issues on internal calls only

[dsm600rr]

Hello all,

So we have a client running IPO Server Edition on a Virtual Machine in the 11:11 Cloud.

They have multiple locations that call each-other internally and its is fine aside from one random user.

He reports: "When I call or they call from any internal line after a few seconds It sounds like I’m in a can then a loud buzzing almost dial tone sound Comes in and neither person can hear the other then call drops”.

He reports this only happens when calling 2 of the remote locations in particular, out of the 5. The real strange thing is, one of the "trouble" locations is connected direct via fiber to his.

We have tried swapping the switch port he is using, tried swapping phones (J169), deleted and re-created his extension and confirmed with their IT: SIP ALG is disabled, firewall rules allow bi-directional RTP streams, and confirmed VPN isn't doing any packet inspection/firewall rules interfering. We have messed with Direct media path and who knows what else over the last 6 months. It seems to come and go.

My thought was to run a PCAP off a mirrored switch port to see if anything pops out while duplicating the issue, however their switch cant do that per IT. Correct me if I am wrong however I don't believe I can PCAP off the PC Port off the back of the J169, correct?

Suggestions? Thanks!

 

[IPOriface]

I don't believe I can PCAP off the PC Port off the back of the J169, correct?

Correct!!

We have a few little port mirroring devices, much easier than messing around with a customer's switch (and trusting their IT to get the mirroring right lol). An old laptop running Mint Linux & Wireshark with a 5TB USB drive for logging lets us leave it in a rack (or elsewhere) for extended captures. Sticking one of these behind a phone is very handy and quick (and can just be run off a normal laptop).

 

[dsm600rr]

Correct!!

We have a few little port mirroring devices, much easier than messing around with a customer's switch (and trusting their IT to get the mirroring right lol). An old laptop running Mint Linux & Wireshark with a 5TB USB drive for logging lets us leave it in a rack (or elsewhere) for extended captures. Sticking one of these behind a phone is very handy and quick (and can just be run off a normal laptop).

Can you give a bit more info on this setup? I have VMware Workstation Pro on my laptop so I can install Mint Linux on that.

 

[IPOriface]

Can you give a bit more info on this setup? I have VMware Workstation Pro on my laptop so I can install Mint Linux on that.

Grab something like one of these: https://www.midbittech.com/index.html
I can't remember the brand of the ones we use, but they're conceptually the same as these - input and 2 outputs with all incoming packets replicated to both output ports.

You patch your laptop into one of the outputs and the phone (or IP500 or whatever) into the other.

If you're not planning on leaving your laptop on site, then you can install wireshark https://www.wireshark.org/ directly on your laptop, and when you patch into the sniffer, then just run the capture on the laptop's ethernet NIC. Running wireshark from inside a VM might be tricky (or might not) - I've never done it. I try to have it as close as possible to the wire being sniffed.

The only reason I used Mint Linux was the laptop was so old, it didn't support Ubuntu or pretty much any other distro lol. I chose the oldest, crappest laptop so if someone stole it when it was left on site, then it was no great loss.

 

[dsm600rr]

Grab something like one of these: https://www.midbittech.com/index.html
I can't remember the brand of the ones we use, but they're conceptually the same as these - input and 2 outputs with all incoming packets replicated to both output ports.

You patch your laptop into one of the outputs and the phone (or IP500 or whatever) into the other.

If you're not planning on leaving your laptop on site, then you can install wireshark https://www.wireshark.org/ directly on your laptop, and when you patch into the sniffer, then just run the capture on the laptop's ethernet NIC. Running wireshark from inside a VM might be tricky (or might not) - I've never done it. I try to have it as close as possible to the wire being sniffed.

The only reason I used Mint Linux was the laptop was so old, it didn't support Ubuntu or pretty much any other distro lol. I chose the oldest, crappest laptop so if someone stole it when it was left on site, then it was no great loss.

Much appreciated! I will take a look at all this. Have a great weekend!

 

[dsm600rr]

Looks like we are going to pick up a SharkTapUSB Ethernet Sniffer however it wont be here by Monday and we will be there doing some other stuff.

I will go back with the SharkTapUSB Ethernet Sniffer, however while I am there doing other stuff I figure I can run SysMon and see if anything sticks out.

What filters would you run in addition to the default?
- Phones are J169s, I will enable "Sip" - just not sure if I want "Verbose", "Standard" or "Terse" - Guessing just standard?

Thanks Gents!

 

[derfloh]

Maybe sit can run Wireshark on your computer, while connected weg a softphone like Workplace.

 

[IPOriface]

Looks like we are going to pick up a SharkTapUSB Ethernet Sniffer however it wont be here by Monday and we will be there doing some other stuff.

I will go back with the SharkTapUSB Ethernet Sniffer, however while I am there doing other stuff I figure I can run SysMon and see if anything sticks out.

What filters would you run in addition to the default?
- Phones are J169s, I will enable "Sip" - just not sure if I want "Verbose", "Standard" or "Terse" - Guessing just standard?

Thanks Gents!

Yep I'd start with Standard, and after you've run the trace, there are some pretty handy VoIP options where Wireshark assembles the call for you, and lets you replay it (including audio) as well as analysing the info. Doesn't always work, but it's a good place to start.