[Bloat] Updated Bufferbloat Test

[Mikael Abrahamsson]

On Thu, 25 Feb 2021, Simon Barber wrote:

> The ITU say voice should be <150mS, however in the real world people are 
> a lot more tolerant. A GSM -> GSM phone call is ~350mS, and very few 
> people complain about that. That said the quality of the conversation is 
> affected, and staying under 150mS is better for a fast free flowing 
> conversation. Most people won't have a problem at 600mS and will have a 
> problem at 1000mS. That is for a 2 party voice call. A large group 
> presentation over video can tolerate more, but may have issues with 
> talking over when switching from presenter to questioner for example.

I worked at a phone company 10+ years ago. We had some equipment that 
internally was ATM based and each "hop" added 7ms. This in combination 
with IP based telephony at the end points that added 40ms one-way per 
end-point (PDV buffer) caused people to complain when RTT started creeping 
up to 300-400ms. This was for PSTN calls.

Yes, people might have more tolerance with mobile phone calls because they 
have lower expectations when out and about, but my experience is that 
people will definitely notice 300-400ms RTT but they might not get upset 
enough to open a support ticket until 600ms or more.

-- 
Mikael Abrahamsson    email: swmike at swm.pp.se