So perhaps this can feed into the rating system, total latency < 50mS is an A, < 150mS is a B, 600mS is a C or something like that. Simon On February 25, 2021 5:49:26 AM Mikael Abrahamsson wrote: > 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@swm.pp.se