4 ms·

Voice over IP: Protocols and Standards (1999)

14 points by gone35 5y ago

whall6 5y ago
This is good. What would also be cool is some info on how they tackle the quality problem! Between 1999 and now they’ve made some huge strides
- supertrope 5y ago
  VoIP is as good as the underlying network. Consistently high quality calls requires packet prioritization which is only possible on a private network not the Internet. Many landline services are VoIP on the backend (phone jack on broadband modem) and there's few quality complaints as voice packets are prioritized across the broadband link and arrive at a phone switch never touching the Internet. On cellphones normal calls are prioritized LTE data. Using your laptop's lid microphone over Wi-Fi over best effort broadband is a house of cards. Internet age codecs like Opus are better able to cope with adverse network conditions compared with G.711 but can't smooth over them entirely. Your ISP is only going to prioritize their integrated VoIP service unless you buy a $$$$ enterprise connection that will honor your packet priority tags.
  - raarts 5y ago
    I would imagine Covid-19 greatly increased customer demand for good quality udp transport. Anyone has more insight to offer here?
    - supertrope 5y ago
      MPLS and DIA connections provide that but cost hundreds of dollars per month. Consumer broadband is affordable because it’s oversubscribed/shared and not dedicated. Average people won’t pay $800/mo and should use their phone as their Zoom audio if they need guaranteed quality.
      - raarts 5y ago
        Yes but I imagine the increased pressure for quality from people working from home would force ISP's to either switch Zoom and others to QoS, or just increase the quality of their network wrt udp in general.
  - bewo001 5y ago
    The network is one aspect of a good voice call. The end devices play a surprisingly big role. A couple of years ago we were hunting down a VoIP packet delay variation problem. We placed fiber taps between all elements and did tons of traces only to find that a popular type of CPE was at fault. The delay variation was there before it hit the network. When HQ voice was introduced, we often measured higher acoustical noise as many phones' microphones and speakers bad quality was now exposed by the improved bandwidth. The funny thing is, now that we have VoIP with expensive, carefully managed priority classes for telephony every business is using plain Best Effort Internet for Zoom and Webex calls.
userbinator 5y ago
Interoperability In a public network environment, products from different vendors need to operate with each other if voice over IP is to become common among users. I believe SIP, and H.323 to a lesser extent, are used extensively in enterprise deployments, but it's sad that all the popular consumer stuff is based on proprietary protocols and essentially does not interoperate. That said, a few times I've been invited to calls with a SIP URI, and pleasantly surprised that I didn't need to download yet another several-hundred-MB app just to join.
- car 5y ago
  Just imagine if FaceTime had become an open standard… That was the plan when it was first presented by Steve Jobs [0]. [0] https://appleinsider.com/articles/10/06/08/inside_iphone_4_facetime_video_calling https://appleinsider.com/articles/10/06/08/inside_iphone_4_f...
  - userbinator 5y ago
    I did a bit more digging and it seems like FaceTime is mostly SIP with some proprietary changes, yet in the decade or so since it was introduced, it's strange that no public thirdparty clients have appeared. I wonder if that's due to threats of legal action from Apple, lack of interest, or something else.
- minipci1321 5y ago
  Many (most by now?) consumer cable networks use SIP (check out PacketCable 2.0) and still don't/wouldn't interoperate. There is much more to voice calling than just SIP, big part of that is attaining guaranteed acceptable quality.

14 points by gone35 5y ago

This is good. What would also be cool is some info on how they tackle the quality problem! Between 1999 and now they’ve made some huge strides

supertrope 5y ago
VoIP is as good as the underlying network. Consistently high quality calls requires packet prioritization which is only possible on a private network not the Internet. Many landline services are VoIP on the backend (phone jack on broadband modem) and there's few quality complaints as voice packets are prioritized across the broadband link and arrive at a phone switch never touching the Internet. On cellphones normal calls are prioritized LTE data. Using your laptop's lid microphone over Wi-Fi over best effort broadband is a house of cards. Internet age codecs like Opus are better able to cope with adverse network conditions compared with G.711 but can't smooth over them entirely. Your ISP is only going to prioritize their integrated VoIP service unless you buy a $$$$ enterprise connection that will honor your packet priority tags.
- raarts 5y ago
  I would imagine Covid-19 greatly increased customer demand for good quality udp transport. Anyone has more insight to offer here?
  - supertrope 5y ago
    MPLS and DIA connections provide that but cost hundreds of dollars per month. Consumer broadband is affordable because it’s oversubscribed/shared and not dedicated. Average people won’t pay $800/mo and should use their phone as their Zoom audio if they need guaranteed quality.
    - raarts 5y ago
      Yes but I imagine the increased pressure for quality from people working from home would force ISP's to either switch Zoom and others to QoS, or just increase the quality of their network wrt udp in general.
- bewo001 5y ago
  The network is one aspect of a good voice call. The end devices play a surprisingly big role. A couple of years ago we were hunting down a VoIP packet delay variation problem. We placed fiber taps between all elements and did tons of traces only to find that a popular type of CPE was at fault. The delay variation was there before it hit the network. When HQ voice was introduced, we often measured higher acoustical noise as many phones' microphones and speakers bad quality was now exposed by the improved bandwidth. The funny thing is, now that we have VoIP with expensive, carefully managed priority classes for telephony every business is using plain Best Effort Internet for Zoom and Webex calls.

userbinator 5y ago

Interoperability In a public network environment, products from different vendors need to operate with each other if voice over IP is to become common among users. I believe SIP, and H.323 to a lesser extent, are used extensively in enterprise deployments, but it's sad that all the popular consumer stuff is based on proprietary protocols and essentially does not interoperate. That said, a few times I've been invited to calls with a SIP URI, and pleasantly surprised that I didn't need to download yet another several-hundred-MB app just to join.

car 5y ago
Just imagine if FaceTime had become an open standard… That was the plan when it was first presented by Steve Jobs [0]. [0] https://appleinsider.com/articles/10/06/08/inside_iphone_4_facetime_video_calling https://appleinsider.com/articles/10/06/08/inside_iphone_4_f...
- userbinator 5y ago
  I did a bit more digging and it seems like FaceTime is mostly SIP with some proprietary changes, yet in the decade or so since it was introduced, it's strange that no public thirdparty clients have appeared. I wonder if that's due to threats of legal action from Apple, lack of interest, or something else.
minipci1321 5y ago
Many (most by now?) consumer cable networks use SIP (check out PacketCable 2.0) and still don't/wouldn't interoperate. There is much more to voice calling than just SIP, big part of that is attaining guaranteed acceptable quality.