Unwanted delay in forwarded calls

Hi all,

I’m just trying to get some help trying to find my way in troubleshooting delays in the different legs of a call.

We have an issue on a setup where in some particular calls a great amount of delay occurs, and in others not.
I’m hoping you guys and girls can help me out trying to make as much as possible call legs ‘visible’ so we can pinpoint where exactly the delays start, and ultimately resolve this issue.

An example of the call: Cellphone calls our customer, that call is incoming in the Freepbx box over a trunk. First thing the pbx does starting to record the call and after that the call is going to be forwarded to an external call center on an hosted voip platform using a dedicated trunk trying to eliminate as much as possible. No details on that external hosted voip platform…
When the call operator on that call center forwards the call to one of the customers cellphones, the delay is the highest. It’s not only noticeable, but it’s very hard to have a normal conversation. My best guess is that the delay is somewhere between 500 and 1000 ms!!!

Our customers setup exists currently of a cable internet connection with more than sufficient bandwidth using a Fortigate firewall.
Trying to eliminate that we also setup a fast 4G connection, no improvement.

Then there is a 1000mbit/s switch, with almost no load. To eliminate that we have also connected all required systems directly onto the router. No improvement there.

Freepbx is on a MS HyperV server 2012 on a HP Proliant DL380 gen8 server with plenty of hardware to spare. Trying to rule that out we have offloaded the Freepbx to another box, with plenty of hardware as well on HyperV Server 2016.
Also tried changing the HytperV guest network card from legacy to the new, modern hyperv Nic.
No improvement here as well.

My best guess is that most of the delay occurs on the cell-to-voip, and on the further end voip-to-cell legs but those are hard to prove. Except as we have the total transit time of the packets, and can measure the other legs that are all running voip.

Oh, and the party that controls the hosted voip platform for the call center is willing to operate but dependent of one of the other large Dutch voip operators.

Anyways, I hope to have some reply(ies) that can help me solve this thing.



I’d say the issue is on their PBX, not yours.

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