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<div dir="auto">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.</div><div dir="auto"><br></div><div dir="auto">Simon</div><div dir='auto'><br></div>
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<div dir="auto">On February 25, 2021 5:49:26 AM Mikael Abrahamsson <swmike@swm.pp.se> wrote:</div>
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<div dir="auto">On Thu, 25 Feb 2021, Simon Barber wrote:</div>
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<div dir="auto">The ITU say voice should be <150mS, however in the real world people are </div>
<div dir="auto">a lot more tolerant. A GSM -> GSM phone call is ~350mS, and very few </div>
<div dir="auto">people complain about that. That said the quality of the conversation is </div>
<div dir="auto">affected, and staying under 150mS is better for a fast free flowing </div>
<div dir="auto">conversation. Most people won't have a problem at 600mS and will have a </div>
<div dir="auto">problem at 1000mS. That is for a 2 party voice call. A large group </div>
<div dir="auto">presentation over video can tolerate more, but may have issues with </div>
<div dir="auto">talking over when switching from presenter to questioner for example.</div>
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<div dir="auto">I worked at a phone company 10+ years ago. We had some equipment that </div>
<div dir="auto">internally was ATM based and each "hop" added 7ms. This in combination </div>
<div dir="auto">with IP based telephony at the end points that added 40ms one-way per </div>
<div dir="auto">end-point (PDV buffer) caused people to complain when RTT started creeping </div>
<div dir="auto">up to 300-400ms. This was for PSTN calls.</div>
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<div dir="auto">Yes, people might have more tolerance with mobile phone calls because they </div>
<div dir="auto">have lower expectations when out and about, but my experience is that </div>
<div dir="auto">people will definitely notice 300-400ms RTT but they might not get upset </div>
<div dir="auto">enough to open a support ticket until 600ms or more.</div>
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<div dir="auto">-- </div>
<div dir="auto">Mikael Abrahamsson email: swmike@swm.pp.se</div>
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