Re: What is Voice over Data Modem ?

Michael Sattler (
Wed, 27 Dec 1995 15:12:01 -0800

At 11:46 12/23/95, wyau wrote:

>I am considering have the following set up at both ends and connected
>via Internet. One through an ISP in HK and the other end through an
>ISP in Thailand.
>486 DX 100
>16M RAM
>Full Duplex sound card
>28.8K Voice over Data modem
>Windows environment
>CuSeeMe/Vidcall alike video conferencing software.
>Can this be done? Or, voice can over data via direct modem dial up?
>What will be the sound quality compare to regular phone?

Having just spent three months in network hell overseas, I think I'm up to
replying. I believe it's correct to say that the gating factor in getting
good performance, bar none, is the number of hops between the two ends.
Even with a screaming CPU and a wonderful 28.8 kbps modem, navigating the
22 hops between my overseas location and my T1-connected machine in the USA
was agony. If you have shell access you can type "traceroute
other-machine-name" and see the number and quality of the path. The values
you get back will change depending upon the load on the net, but a slow
link somewhere in the middle will screw up all real-time connectivity.

That having been said, my next concern is your hardware. A 486 is a wee
bit paltry for serious voice, but it will probably be just enough for
voice-only. Using CU-SeeMe for this is probably the wrong thing to do,
something dedicated for voice-only will probably give you better results.

Keep it simple: use something like IPhone (or is it now called Internet
Phone?). Avoid other CPU overhead. When PGP Fone for Windows is released,
for example, you probably won't enjoy the performance of encrypted voice
transmission: the CPU has to work too hard to give good performance over a
connection such as you specify.

Good luck, and please let me/us know how things go.

Happy Julian new year.

Michael Sattler, Digital Jungle <> |
San Francisco, California, USA <> |
My book "Internet TV with CU-SeeMe" (ISBN 1-57521-006-1) is available! |
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