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Ask HN: Why isn't VoIP better?

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

#21

Post by bsaunder »

So VoIP can be better... at the expense of needing more bandwidth. During the session initialization the two VoIP endpoints handshake over which codecs will be used (kind of like the Accepts header in HTTP). Just like images, higher quality codecs tend to use more bandwidth (though like images its much more nuanced than that). Similarly like image formats there's different amounts of loss in the encoding/decoding of the voice data.

Voice has a major difference though. Its generally a real time protocol (its data packets are called RTP and sent over UDP generally). With images you can afford to wait longer for high quality images to load over a slow network. In a phone call that delay gets a bit annoying (to put it lightly).

Most people would rather trade quality for timeliness. You ISP would rather throttle your bandwidth and may not care about your quality (to a point).

Its quite a bit more complicated than that, but in a nutshell with VoIP, "higher quality" = "more bandwidth". If you don't have the bandwidth you'll have a very hard time getting better quality. If you have the bandwidth locally, then your provider or some network link along the way either doesn't have the aggregate capacity or may be actively throttling your rate to limit usage.

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

#23

Post by scandox »

MandieD wrote: post #18
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.

At home I use Ethernet, a Blue Yeti USB microphone and a solid pair of Philips USB headphones. Of course I don't know what my counterparts on the other end are using.

I guess my problem seems to be that we swapped a system that had a consistent call quality for one that is inconsistent, for a whole bunch of reasons. It seems to me, as if the general quality of telephony took a huge step backwards. And I don't understand, in an age of technical progress, why we should (or do) put up with that.

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

#24

Post by Xophmeister »

scandox wrote: post #17
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.

Never is a long time. What if some day the technology exists to interpolate dropped packets (e.g., using ML) fast and cheaply enough to fill in the distortion? That doesn't seem too outlandish in the next 20, or even 10 years.

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

#25

Post by VLM »

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.

Its bandwidth efficiency, latency, and jitter, actually.

Just like in the old days of 9600 baud leased lines it was hard to get acceptable console performance, and now people have megabit connections and CLI performance is not unusually constrained over the megabit connections. Of course its only using a fraction of 1% of the capacity.

Also remember that end users might have megs of bandwidth to carry K of voice traffic, but somewhere along the line there's someone constrained. Just like work offices don't have to be dumps, but its hard to put a beancounter $ value on not working in a dump, leads to a lot of open office foolishness.

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

#26

Post by mikekchar »

bsaunder wrote: post #22
zamalek wrote: post #8

It's probably because most people have horrible quality microphones.

Sorry to down vote, but that's completely the wrong vector. Its a network issue (of some sort - bandwidth, latency, throttling).

Yeah, if you see the quality (or lack thereof) of microphones in old telephone handsets you'd be amazed.

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

#27

Post by MandieD »

scandox wrote: post #23
MandieD wrote: post #18

Earlier quoted context omitted.

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.

At home I use Ethernet, a Blue Yeti USB microphone and a solid pair of Philips USB headphones. Of course I don't know what my counterparts on the other end are using. I guess my problem seems to be that we swapped a system that had a consistent call quality for one that is inconsistent, for a whole bunch of reasons. It seems to me, as if the general quality of telephony took a huge step backwards. And I don't underst…

Are the 1 in 3 good calls pretty random, or do they tend to be with the same counterparts? Do you notice a difference between the quality of your calls into conferences (if on the same platform) and direct calls with colleagues?

WiFi can be a source of the problem even within the corporate network if the access points weren't designed for VoIP.

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

#28

Post by scandox »

Xophmeister wrote: post #24
scandox wrote: post #17

Earlier quoted context omitted.

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.

Never is a long time. What if some day the technology exists to interpolate dropped packets (e.g., using ML) fast and cheaply enough to fill in the distortion? That doesn't seem too outlandish in the next 20, or even 10 years.

That sounds fine, except for the timeline. What I'd like is an affordable, ubiquitous solution next week :)

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

#29

Post by bsaunder »

Old fashioned PSTN lines would secure the full bandwidth needed end-to-end when the original call was established (which was really in efficient from a data utilization perspective).

With VoIP you are:

1. Beholden to the bandwidth/latency issues of the crappiest link in your end-to-end path.

2. Intentional use of poorer quality codecs (by your ISP and/or VoIP software to reduce aggregate bandwidth use). Ironically this can be inverted, there are codecs that sound much better than PSTN calls (but use more bandwidth).

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

#30

Post by MandieD »

scandox wrote: post #23
MandieD wrote: post #18

Earlier quoted context omitted.

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.

At home I use Ethernet, a Blue Yeti USB microphone and a solid pair of Philips USB headphones. Of course I don't know what my counterparts on the other end are using. I guess my problem seems to be that we swapped a system that had a consistent call quality for one that is inconsistent, for a whole bunch of reasons. It seems to me, as if the general quality of telephony took a huge step backwards. And I don't underst…

The only thing that could make VoIP voice quality as consistent as PSTN is a consistent application of QoS.

And that is why I have very mixed feelings about Net Neutrality. Sure, I don't think that Verizon should be allowed to penalize NetFlix or $randomVideoStartup by favoring its video traffic over theirs, but there is no technical way for voice to be consistently good without a consistent handling of its data traffic.

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