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  • #26265 Reply

    Hi everyone,
    Hard to believe but I will not have ADSL available before another 12-18 months in my area (Provence South of France) and would like to know if a 128k ISDN connection is sufficient to make use of VOIP technology for one user?

    Also, I was thinking of setting up a 128k/512k internet 2way access via satellite but I am told VOIP is not possible due to uncompressible latency delay of 550-660ms distance to satellite 36?000km. Does anyone knows if this is correct?

    If anyone could shed some lights on these subjects that would be great.



    #26266 Reply
    Noname to Kris

    No sweat, my friend. I have ADSL with only 64 kb in South America, and that is plenty for one channel.

    They only give me around 54-56 kb on the “64” kb, and is plenty for a Quintum A200 to run one channel.

    If you get ISDN, with only one channel active, at least in theory, you may be able to run three channels at the same time.

    Two calls will be more realistic, but still no more than 25 kb per call,using tre G729 codec (that is not the lowest rate codec, but very popular)

    But by all means, do noy buy a Quintum A200. They are bad news.

    Any other quintum, I give them the benefit of the doubt. But about the A200, I am SURE!!!!!!

    It is a piece of trash!!!

    #26267 Reply

    Hello Kris, Noname,
    To address your questions. A latency of 550-660ms is a little bit high for voip. However 128kbps is plenty enough bandwidth to run 3-4 lines using g.729 or g.723. So the voice quality will not suffer, however there will be a noticeable delay in the voice transmission. I’ve heard voip calls on similar satellite setup’s. The delay is not the worse than anything i’ve heard from a long distance call over a land line. Also about the A200, they have been discontinued by quintum. They were the only unit that Quintum didn’t build themselves. You definately want to stay away from it, as it does not have the high quality and reliability of the other Quintum units. If you have any questions about implementation of voip send me an email at

    #26268 Reply

    Thanks for your replies.
    So, in theory it is possible to use VOIP over a satellite connection if we don’t mind the latency delai.
    The 2way satellite providers I contacted in France all said no VOIP can be effectively used on their channels.
    But now I start to think it is more an excuse to limit the quantity of data transmission as satellite channels are share with other users.
    I think I will go for a 128k/512k satellite internet connection as the monthly rental is about the same as an unlimited ISDN, with the distinct advantage to allow shared use with neighbours over a Mesh Network for example.
    Thanks for the info on the Quintum’s.

    #26269 Reply

    It is not the bandwidth that you have to be concerned about on sat it is the TDMA (time delay) that messes up VoIP sometimes.

Viewing 5 posts - 1 through 5 (of 5 total)
Reply To: VOIP over ISDN
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