giving up on VOIP?

Discussion in 'VOIP' started by Len Hightower, Dec 8, 2003.

  1. I have noticed several people complaining about Vonage, packet8, et
    all and giving up the services. I wonder how often the problem is in
    the Internet connection as opposed to the VOIP service provider. My
    experience was that when I initially got packet8, the service was
    excellent. Then, after a move to another home and a new ISP, the
    service went to hell in a hat basket. I was convinced that it was
    Packet8 since the Internet connection "seemed" to be working fine.
    Only by accident, did I notice thet my cable modem would occasionally
    go out of sync. The problem only lasted for a few seconds but I
    noticed that it coincided with drop outs on packet8 calls. A call to
    the Cable company's tech support resulted in my finding out that my
    cable modem was going out of sync SEVERAL HUNDRED TIMES A DAY!! A few
    tweaks at the cable company's office solved the problem and packet8
    was back to being superb again. So good, in fact, that I dumped SBC
    shortly afterwards. Just a thought.
     
    Len Hightower, Dec 8, 2003
    #1
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  2. I would think that Packet8's solution would compensate for this kind of
    problem. They're selling this to customers to use on the Internet, right?
    So the expecaction would be that they could forsee circumstances such as
    yours. When you say the service "went to hell in a hat basket" - what
    exactly do you mean? Perceived quality was bad? Calls dropped or not
    connected? I'm just curious because I work in this field, and while our
    products are aimed mostly at corporate business with their own networks -
    I've always wondered just how bad things would get when implemented over a
    real, lossy network.

    J
     
    James Calivar, Dec 8, 2003
    #2
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  3. Len Hightower

    Lonewolf Guest

    One thing that can't be ignored is that VoIP is sensitive to delay, latency,
    jitter and packet loss. If your ISP connection causes any of this, then the
    problem is with the ISP. I doubt that any of the VoIP providers ignore this
    in their networks, but their control stops at the ISP level. The Internet
    doesn't implement any sort of QOS to prioritize anything..
     
    Lonewolf, Dec 8, 2003
    #3
  4. Len Hightower

    Terry Aki Guest

    This is all true, but any VoIP gateway or IP Phone provider worth its salt
    will be incorporating all sorts of tricks to comensate for this kind of
    packet degradation. True, the povider cannot predict how good or bad the
    performance of a user's network would be, but with appropriate confoguration
    settings, it should be able to provide reasonable quality voice even in
    severe conditions.
     
    Terry Aki, Dec 9, 2003
    #4
  5. Len Hightower

    Lonewolf Guest

    The tricks seem to be few and far between, I believe because of the limited
    possibilities and virtual lack of control of the Internet. After all,
    there's been an IP addressing problem in the Internet for years and a
    solution (IPV6) has been available for about 10 years. I'm still unaware of
    anyone planning an implementation to resolve it.

    The configuration possibilities exist today to greatly improve VoIP quality
    through the Internet, but I don't see their implementation coming anytime
    soon. Everyday I implement these capabilities in private networks, but until
    there is some measure of control of the Internet I don't see things getting
    much better.
     
    Lonewolf, Dec 9, 2003
    #5
  6. Len Hightower

    Lonewolf Guest

    The tricks seem to be few and far between, I believe because of the limited
    possibilities and virtual lack of control of the Internet. After all,
    there's been an IP addressing problem in the Internet for years and a
    solution (IPV6) has been available for about 10 years. I'm still unaware of
    anyone planning an implementation to resolve it.

    The configuration possibilities exist today to greatly improve VoIP quality
    through the Internet, but I don't see their implementation coming anytime
    soon. Everyday I implement these capabilities in private networks, but until
    there is some measure of control of the Internet I don't see things getting
    much better.
     
    Lonewolf, Dec 9, 2003
    #6
  7. Len Hightower

    Terry Aki Guest

    I'm not talking about tricks to play on the network itself; I'm talking
    about tricks to play in the gateways, such that you can *counteract* those
    nasty conditions on the Internet. Packet loss? Fine. Use intelligent
    algorithms during reassembly of your voice datastream in order to mask their
    perceptual effects. Data redundancy, FEC, interpolation - all of these
    things can be used. Lots of ineter-packet arrival time variation? This is
    what a jitter buffer is designed to overcome. I admit that long end-to-end
    delays are difficult to couteract, but reducing the gateway's processing and
    playout delay as much as possible can alleviate this problem somewhat. And
    it helps to use a low-overhead trasnport protocol like UDP.

    As far as I know, voice over the internet will never equal in quality that
    which you can attain on a managed network. But that's the price you pay for
    getting free voice communications.
     
    Terry Aki, Dec 9, 2003
    #7
  8. Much of the continent of Asia, for starters.
     
    Melinda Shore, Dec 9, 2003
    #8
  9. Almost all VoIP-systems use UDP together with RTP to transfer the
    audio-stream. And while you can do some stuff to compensate for
    packet-loss and jitter, this also has drawbacks. If you include redundancy
    information (as it is done in T.38 for fax for example), your bandwidth-
    requirements start to rise considerably. If you have a larger jitter-buffer
    you pay this by having much longer latency, which could leave a call
    in a state that is almost useless.

    So unless the network/isp supplies a minimum amount of quality your are
    really out of luck and there's nothing your VoIP-provider can do to
    remedy this situation.

    Tobias
     
    Tobias Erichsen, Dec 10, 2003
    #9
  10. Len Hightower

    Terry Aki Guest

    Yes, all of that is true. Having an ISP that delivers decent qulaity is a
    high priority. But I think that voice over the Internet is still viable.
    In fact I *know* it is. Besides my job, my school and my family, one of my
    hobbies is computer gaming. I use a program called "TeamSpeak" that allows
    myself and my teammates in a game to converse in realtime using cheap
    headsets with microphones. I'm not certain of what technology goes into
    this program, but it's probably not a lot more complicated than a suite of
    voice codecs of various rates, and a minimally complex voice playout
    algorithm. The quality of the voice is never terribly good, but it's
    understandable, and the best pasrt is it's free!

    By the way, as far as redundancy goes in T.38, you're really not incurring
    any significant bandwidth/data rate increase if you configure the gateways
    in a smart fashion. True, one can configure the gateway, for example, to
    insert 3x redundancy in the actual page data, where the highest data rates
    exist. But this comes at a very high cost for relatively little payoff in
    terms of page qulaity. The most critical place to insert redundancy is in
    the 300bps handshake data, inorder to prevent the call from failing
    outright. Even with 8x redundancy in this data stream, you are still only
    incurring the same overall data rate as a 2400bps V.27ter call.

    Regards,

    T
     
    Terry Aki, Dec 10, 2003
    #10
  11. This is certainly true - but only in the event that there is an end-to-end
    ECM-connection for page-data. Without this mode, packet-loss will
    result in scan-lines being lost. Obviously most fax-machines support
    ECM nowerdays so this is not much of an issue...

    Tobias
     
    Tobias Erichsen, Dec 10, 2003
    #11
  12. Len Hightower

    Terry Aki Guest

    It's been my experience that when packet loss occurs at "reaonable rates" in
    a non-ECM fax call, the visual quality of the page is not appreciably
    affected. The human brain is remarkably good at interpolating data from
    corrupted visual images! Interestingly, using ECM mode in a moderately
    lossy packet network can actually cause the fax call to fail (from a T.30
    protocol perspective), since the receiving fax machine "insists" on
    receiving perfect page blocks; after several iterations of requesting
    retransmisssion of bad blocks, the fax machine(s) abort the call.

    Also, at least one VoIP/T.38 gateway manufacturer implements a proprietary
    algorithm on the receive side that compensates for packet loss by generating
    blank scan lines. This alleviates the problems some fax machines have when
    receiving many bad scan lines, whee they go on-hook if some threshold of
    received bad scan lines is crossed.

    So like I was saying, there are a lot of tricks that can be played to
    compensate for a crappy network (both voice and fax/data traffic), but in
    the end, you can only do so much. It is hoped that the state of the
    Internet today is much more reliable than in the past!

    T
     
    Terry Aki, Dec 10, 2003
    #12
  13. The problem is we are just on the cusp of having enough bandwidth
    commonly available for voip as done by vonage. (I don't know about
    packet8 but Vonage uses g711, which takes about 80 kbits/s each way
    with overhead, which is a risk on any adsl or cable modem with limited
    upstream.)

    There are those who argue there is no need for QoS, it is always cheaper
    to just provision more bandwidth, but we aren't at that level yet.

    Unfortunately, providers who offer POTS over IP (which is pretty much
    what you get from Vonage and Packet8) are not going to be able to cut
    it. The TDM telcos have better reliablity in the network, and much
    better at the endpoint. Your phone does not go down in power outages,
    or if you are doing a giant download/upload or have an internet outage.

    So people will not want to just use VoIP to pay less. They must
    provide customers with compelling alternate features, not just price.
     
    Brad Templeton, Dec 10, 2003
    #13

  14. And Microsoft, which has released a solution to deploy IPv6 in all
    windows boxes, which millions have already downloaded. MS has the
    power to make it so here, more than anybody in the world, so I think
    we'll see it soon.
     
    Brad Templeton, Dec 10, 2003
    #14
  15. Well, if you're going to talk about operating systems,
    pretty much all contemporary OSes support v6, including the
    various Unixes, MacOS, and the current versions of Windows.
    Routers (real routers) do, as well, and it's just a matter
    of using it. And using it is not that big a deal, with the
    availability of services like Freenet6.

    What we need is application support for v6, and this is
    where Microsoft is not following through on their public
    comments. (Mozilla supports v6, incidentally).
     
    Melinda Shore, Dec 10, 2003
    #15
  16. Len Hightower

    Miguel Cruz Guest

    As you say, though, we're on the cusp of having enough bandwidth. My
    home DSL bandwidth has been going up while the price goes down, and I
    haven't had any outages for years except for a couple minutes earlier this
    year.

    The power outage thing is an issue in some places, I guess. But cell phones,
    which are becoming quite common, or so I'm told, can fill in that gap.

    miguel
     
    Miguel Cruz, Dec 10, 2003
    #16
  17. Dropped calls, warbled voice, calls not being connected. Just general
    unreliability.
     
    Len Hightower, Dec 12, 2003
    #17
  18. Dropped calls and calls not being connected are, to me, unnacceptable. If
    the Packete8 solution is using some sort of non-guaranteed packet transport
    mechanism to convey signaling (such as UDP instead of TCP), then one could
    expect this kind of problem. Actually, dropped calls concern me even more
    that the ones that weren't conneted in the first place. You're talking
    about just a voice call, right? No modem or fax traffic? Once the call is
    set up, if packet loss occured, sure you'd get crummy quality, but the call
    should remain alive. It should *not* tear down no matter what you do (short
    of hanging up) or what happens on the network.
     
    James Calivar, Dec 12, 2003
    #18
  19. Len Hightower

    shope Guest

    The OP was talking about dropouts - which are nothing to do with the
    bandwidth available - it is all about when you get an interruption in
    forwarding.

    The earlier thread about error correction is not looking at what VoIP is
    trying to do.

    If you want voice conversations with a reasonable round trip delay to
    emulate a conventional voice connection then you need to limit delay across
    the IP link (we design to 150 mSec on IP Telephony systems at work for high
    quality).

    If the max delay you can impose on a packet is 150 mSec then you cant use
    error correction to fill in for anything above some smaller amount of time
    (unless you can predict what the person will say before they get around to
    it) - commercial G.7xx CODECs normally can cover for 30 mSec of missed data.

    So - retraining a cable modem is going to take 10s of seconds.....If your
    call vanishes for say 1 minute - even if the connection survives you are
    likely to give up in disgust.
    QoS is an issue when the link overloads, or you get short term congestion
    across the path.

    But QoS only gives you better service at the expense of other connections
    sharing the same links. And only when you have something that is already
    fairly close to good enough - adding QoS is no substitute for an underlying
    reliable network.
    but - there have been fires in telephone exchanges that have taken entire
    towns out of service.

    and if your IP phone was that critical, then wouldnt you connect everything
    to a UPS?
    I work on corporate telephony networks, where sometimes the primary
    requirement is lower cost - but voip does give you a different set of
    tradeoffs compared to TDM based telephony.
     
    shope, Dec 13, 2003
    #19
  20. Len Hightower

    No.6 Guest

    Try VoicePulse
     
    No.6, Dec 14, 2003
    #20
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