Teams Business Voice Call Latency

[davegravy]

Teams call latency is waaaay better than we were getting with our previous VOIP provider (Mitel) but I still felt it was a bit worse than PSTN->PSTN calling. I grabbed an audio recorder and audio editing software and did some testing to see what the actual mouth to ear latency was.

• PSTN (Bell Canada Cell Network) to Windows (Teams): 450ms

• Windows (Teams) to PSTN (Bell Canada Cell Network): 630ms

• Total round trip: 1080ms

For reference, the general accepted round trip latency limit for decent call quality is 300ms ( https://www.lifewire.com/what-is-latency-and-how-it-can-be-reduced-3426314, https://getvoip.com/blog/2018/12/20/acceptable-jitter-latency/ )

1080ms leaves something to be desired. It's workable but I still find parties interrupting each other on calls fairly often. I didn't test PSTN->PSTN but I'm sure it will be much lower.

For reference, my Windows desktop is on a gigabit fiber internet connection with 4ms latency to Google DNS servers. At the time of testing there was very little utilization of my internet link or the compute resources of my fairly modern Windows desktop.

I'm curious as to how much the recent surge in Teams demand is a factor here and how much of this latency is base system latency. Has anyone else done measurements like these? 

[#2]

I appreciate the detail of your testing @davegravy, I am just running a POC now and am testing a multi region deployment, I have had some test calls within the EU and within the US, I found that the latency was unnoticeable on my EU based calls (user in EU calling via SBC and VG in EU to a cell phone in the EU).

But the calls in the US are experiencing about a 1 second latency for calls routing from a US based Teams user > Via US based SBC & VG > US cell phone.

We will have to record it and confirm if this issue is a US only based issue.

Now, I did run a test where I connected to a VPN gateway in Japan to force my client to route from Japan. In that call where I was looping my voice traffic around the world (from EU) I was getting about a 2 second delay.

Makes we wonder if the NSA is forcing MS Teams traffic via their DC for them to monitor communications.