my attempt at VoIPoCDMA2000

Discussion in 'VOIP' started by Kyler Laird, Nov 4, 2004.

  1. Kyler Laird

    Kyler Laird Guest

    I would love to have some (wide area) mobile VoIP phones.
    I've been searching for a solution for awhile and finally
    decided to just see how bad it would be to use a current
    mobile phone network to achieve this functionality.

    I've been a SprintPCS user for years so after getting
    reports of sub-400ms ping times, I decided to give their
    data card a try. The nearest stores (in Indy) only had
    the Novatel Wireless Merlin C201 so that's what I got.

    As has been reported, after initializing this card (under
    MS Windows) it is readily usable by Linux. Once up (as a
    PPP device), it yielded ping times mostly in the 300 to
    400ms range. It seemed fairly robust. I didn't get the
    many-second-long silences that I expect from GPRS.
    --- yahoo.com ping statistics ---
    50 packets transmitted, 50 received, 0% packet loss, time 49431ms
    rtt min/avg/max/mdev = 307.951/453.274/1437.838/214.054 ms, pipe 2

    I discovered that port 80 is run through a transparent
    HTTP proxy. (Some of my photos were recompressed.) Most
    communications seemed unfettered though. Unfortunately,
    when I tried using a SIP phone over this connection it
    failed to even register. I suspect timing was the issue
    but I don't have an eye for spotting SIP problems. (The
    packets seemed to be passing o.k.)

    Recently I found iaxComm, an IAX softphone. I decided to
    give it a whirl and it registered without any problems.
    Making calls seemed o.k. and the audio was decent. When
    I tried to send audio, however, it fell apart. It
    *really* chokes on ulaw (of course) but even GSM is
    unusable.
    50 packets transmitted, 50 received, 0% packet loss, time 49007ms
    rtt min/avg/max/mdev = 366.003/1182.807/2815.567/536.911 ms, pipe 3

    I like having this card but the latency is too high for
    me to justify keeping it at $80/month. I'm hoping for
    UMTS to arrive someday soon...

    --kyler
     
    Kyler Laird, Nov 4, 2004
    #1
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  2. Kyler Laird

    carcarx Guest

    Thanks for letting us know about your experiment.

    I tethered my Sanyo 6400 to my XP Pro laptop and tested Skype.

    It sounded fine, but had occasional packet delay.
    (The audio fidelity of Skype is awesome!)
     
    carcarx, Nov 4, 2004
    #2
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  3. Kyler Laird

    Central Guest

    On Thu, 04 Nov 2004 02:08:05 +0000, Kyler Laird wrote:
    <snip>
    >
    > Recently I found iaxComm, an IAX softphone. I decided to
    > give it a whirl and it registered without any problems.
    > Making calls seemed o.k. and the audio was decent. When
    > I tried to send audio, however, it fell apart. It
    > *really* chokes on ulaw (of course) but even GSM is
    > unusable.
    > 50 packets transmitted, 50 received, 0% packet loss, time 49007ms
    > rtt min/avg/max/mdev = 366.003/1182.807/2815.567/536.911 ms, pipe 3
    >
    > I like having this card but the latency is too high for
    > me to justify keeping it at $80/month. I'm hoping for
    > UMTS to arrive someday soon...
    >
    > --kyler


    The main problem with sprintpcs data network is that it is an a-sync
    burst-able medium. ULAW, if I recall is 64kbit/s audio or around 8KB/s
    both ways while GSM is 13kbit/s or around 1.6KB/s both ways. Main issue
    you were running into was mostly likely packet loss due to the connection
    being utilized both up/downstream at those rates. You might want to look
    into some of the commercial codecs like G.729 which would be around
    9kbit/s or around 1.1KB/s both ways. For the most part gsm should have
    enough bandwidth it is just that since the sprintpcs data network is
    burst-able and focuses on high downstream rates you sometimes run into an
    issue where you have good incoming line but outgoing falls apart. Of
    course this also varies by location, how many people are active on the
    pipe providing the tower, etc. As far as latency is concerned I doubt you
    will find anything in the 200-300ms range cheap. After all in most cases
    the signal still has to travel at least half a mile to the tower and then
    spider through sprintpc's internal network first. Most of the time I avg
    600ms with spikes up to 1300ms when using the connection. As always your
    mileage will vary.
     
    Central, Nov 4, 2004
    #3
  4. Kyler Laird

    Kyler Laird Guest

    "carcarx" <> writes:

    >(The audio fidelity of Skype is awesome!)


    Yeah, I've heard iLBC is worth using but I haven't gotten it
    configured in Asterisk and iaxComm yet. Think that'll make a
    significant difference?

    --kyler
     
    Kyler Laird, Nov 4, 2004
    #4
  5. Kyler Laird

    yum Guest

    I believe that SprintPCS PTT(Push To Talk) feature is VoIP on CDMA2000. It
    uses the same concept of VoIP in the wireless mobile phone. It should work.
    UMTS will not be better that CDMA2000 EVDO.


    "Kyler Laird" <> wrote in message
    news:...
    >I would love to have some (wide area) mobile VoIP phones.
    > I've been searching for a solution for awhile and finally
    > decided to just see how bad it would be to use a current
    > mobile phone network to achieve this functionality.
    >
    > I've been a SprintPCS user for years so after getting
    > reports of sub-400ms ping times, I decided to give their
    > data card a try. The nearest stores (in Indy) only had
    > the Novatel Wireless Merlin C201 so that's what I got.
    >
    > As has been reported, after initializing this card (under
    > MS Windows) it is readily usable by Linux. Once up (as a
    > PPP device), it yielded ping times mostly in the 300 to
    > 400ms range. It seemed fairly robust. I didn't get the
    > many-second-long silences that I expect from GPRS.
    > --- yahoo.com ping statistics ---
    > 50 packets transmitted, 50 received, 0% packet loss, time 49431ms
    > rtt min/avg/max/mdev = 307.951/453.274/1437.838/214.054 ms, pipe 2
    >
    > I discovered that port 80 is run through a transparent
    > HTTP proxy. (Some of my photos were recompressed.) Most
    > communications seemed unfettered though. Unfortunately,
    > when I tried using a SIP phone over this connection it
    > failed to even register. I suspect timing was the issue
    > but I don't have an eye for spotting SIP problems. (The
    > packets seemed to be passing o.k.)
    >
    > Recently I found iaxComm, an IAX softphone. I decided to
    > give it a whirl and it registered without any problems.
    > Making calls seemed o.k. and the audio was decent. When
    > I tried to send audio, however, it fell apart. It
    > *really* chokes on ulaw (of course) but even GSM is
    > unusable.
    > 50 packets transmitted, 50 received, 0% packet loss, time 49007ms
    > rtt min/avg/max/mdev = 366.003/1182.807/2815.567/536.911 ms, pipe 3
    >
    > I like having this card but the latency is too high for
    > me to justify keeping it at $80/month. I'm hoping for
    > UMTS to arrive someday soon...
    >
    > --kyler
    >
     
    yum, Nov 7, 2004
    #5
  6. Kyler Laird

    Kyler Laird Guest

    "yum" <> writes:

    >I believe that SprintPCS PTT(Push To Talk) feature is VoIP on CDMA2000. It
    >uses the same concept of VoIP in the wireless mobile phone. It should work.


    Latency is hardly an issue for PTT.

    --kyler
     
    Kyler Laird, Nov 8, 2004
    #6
  7. Kyler Laird

    Central Guest

    On Mon, 08 Nov 2004 03:08:05 +0000, Kyler Laird wrote:

    > "yum" <> writes:
    >
    >>I believe that SprintPCS PTT(Push To Talk) feature is VoIP on CDMA2000. It
    >>uses the same concept of VoIP in the wireless mobile phone. It should work.

    >
    > Latency is hardly an issue for PTT.
    >
    > --kyler


    Latency isn't any issue because there is less overhead with PTT. Not to
    mention sprintpcs has their network setup to let PTT through with more
    priority then say your vision web access. I would imagine if PTT had to go
    the same distance/cost as a voip connection from a tethered laptop you
    would have just as much of a latency issue.
     
    Central, Nov 9, 2004
    #7
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