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Ask HN: Why isn't VoIP better?

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Re: Ask HN: Why isn't VoIP better?

#11

Post by biokoda »

VOIP calls are very sensitive to intermittent connectivity.

Sometimes wifi will work in batches. No packets will get through for a few hundreds of milliseconds (or seconds), then they will get sent all at once.

Sometimes UDP traffic is blocked completely and the call has to get relayed over TCP. Now no packets can get dropped and you get delays due to retransmits.

Sometimes 3g/4g connection disappears because someone entered a building an overpass or passed a corner in a city.

Sometimes the sides of the conversation are far and the audio delay is high.

If any side of the conversation encounters a problem described above both will get a bad quality.

Re: Ask HN: Why isn't VoIP better?

#12

Post by dijit »

I don't believe what you ask for can ever exist. "Clear, Distortion Free, Low-Latency. Pick any two" comes to mind.

When you're doing voip you're doing so over UDP because TCP has far too much latency to be agreeable, but this means a lost packet will be a digital distortion. The nature of the internet is that packets get lost or arrive out of sequence- that's why TCP exists in the first place.

Re: Ask HN: Why isn't VoIP better?

#13

Post by Flimm »

scandox wrote: post #4
iopuy wrote: post #2

Where do you live where you can get 2 gigabit speeds at home?

240 Mbps. So AFAIK 240 megabits per second. Is my original notation ambiguous?

A capital B indicates "byte", and a lower-case b indicates "bit". 240 MBps is eight times faster than 240 Mbps.

When it comes to speeds in bits per second, M almost always means 1000000, and not 1048576.

Re: Ask HN: Why isn't VoIP better?

#14

Post by barking »

Could it be the upload speeds or QoS settings? I don't use voip, my wife skypes long distance and it seems pretty good for both video and audio and our internet is only 2ish Mb down and 1ish Mb up!

Re: Ask HN: Why isn't VoIP better?

#15

Post by MandieD »

Jitter is one of the words you're looking for. 20 milliseconds does not sound like much, but when it's a delay in some (but not all) packets in a call getting to you, you can sure hear it!

Jitter is why you could have a 1 GB/s connection at home, and still have the same occurrence of poor call quality.

QoS (Quality of Service) can help, but only if it is applied at every router the traffic for a call goes through. QoS-assured bandwidth is more expensive, and cost-conscious VoIP providers don't seem to be willing to pay for it.

(edited to add) I'm a Skype for Business admin.

Re: Ask HN: Why isn't VoIP better?

#16

Post by guan »

sheepdestroyer wrote: post #9
iopuy wrote: post #2

Where do you live where you can get 2 gigabit speeds at home?

Possibly OP was incorrectly confusing Mbps and MBps but in Japan Sony offers 2Gb/s for home connections. I had their 1Gb/s plan for ~6000JPY/Month when I was living in Kyoto. Was great

How is a 2 Gb/s home connection presented? 10GbE?

Re: Ask HN: Why isn't VoIP better?

#17

Post by scandox »

dijit wrote: post #12

I don't believe what you ask for can ever exist. "Clear, Distortion Free, Low-Latency. Pick any two" comes to mind. When you're doing voip you're doing so over UDP because TCP has far too much latency to be agreeable, but this means a lost packet will be a digital distortion. The nature of the internet is that packets get lost or arrive out of sequence- that's why TCP exists in the first place.

So what you're saying is: VOIP will never match PSTN? Because that's the mood music I get from the sysadmins at work too.

Re: Ask HN: Why isn't VoIP better?

#18

Post by MandieD »

biokoda wrote: post #11

VOIP calls are very sensitive to intermittent connectivity. Sometimes wifi will work in batches. No packets will get through for a few hundreds of milliseconds (or seconds), then they will get sent all at once. Sometimes UDP traffic is blocked completely and the call has to get relayed over TCP. Now no packets can get dropped and you get delays due to retransmits. Sometimes 3g/4g connection disappears because someone…

Among other things, I'm a Skype for Business admin. We've found that having our users use Ethernet when working from home instead of WiFi eliminated a lot of audio quality complaints.

Re: Ask HN: Why isn't VoIP better?

#19

Post by dsr_ »

Single anecdotal counterpoint:

My corporate VOIP system is made of Polycom phones connecting via SIP to local Asterisk servers, and then those have interconnects to PSTN gateway services.

The quality on-campus is uniformly extremely high.

Some people have the Polycom phones at home (for working remotely) and calls to/from those are of similarly high quality, even in conferences.

Connections to cellphones range from mediocre to bad.

Connections to POTS land lines range from bad to pretty good.

Overall I would say that our VOIP system doesn't have a problem.

Re: Ask HN: Why isn't VoIP better?

#20

Post by vacri »

PSTN uses a digital backbone these days; it's just supersized carrier-grade digital backbone, not 'what hacky software can we get on the cheap'. Phone companies prioritise their voice traffic over their own backbone and have network admins monitoring it closely, whereas your skype calls are just 'more traffic from the proles' and get to compete with everyone else.
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