VoIP over satellite link?

We have a customer in a remote area, relatively near the equator (their ISP is too). They don't have much voice coverage (no land lines and scant cell) but they have a satellite-based DSL Internet link. I would like to try to solve their problem with a VoIP ATA from Linksys, because its configuration parameters can be tweaked at will.

I have the obvious concerns: how much will the delay affect voice quality? Is there some TCP/UDP window that should be adjusted? Any question I haven't addressed?


-Ramon F Herrera

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Ramon F Herrera
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Did you ever use one of those old satelite links for a long-distance/overseas call? I suspect that VoIP over a satellite-based DSL link wouldn't even be that good. I have vague memories of speaking with my grandfather over one of those a few times and it did not lend itself to a normal flowing dialog.

Assuming we are talking about a geosync satellite here, that is at least one hop of ~46000 miles each way, which translates to a one-way latency of ~250 milliseconds. (Handwaving math...) And then add-in whatever happens once their voice data hits the regular pots (?) network, and whatever other delays there might be on the IP side at the ISP or whatnot.

So, your customer would say "boo!" and it would be a full half-second before you could say "eek!" No tweaking of TCP windows (UDP has no window) or other stuff could change that. While at first blush half a second might not sound like a big deal, there was a very compelling reason the telcos/whatever put all those trans-oceanic links in :)

rick jones

Reply to
Rick Jones

Hi Rick:

I've set up a lot of VoIP-over-Satellite systems. Yes, the latency is a bit of an issue, but for the most part you can have some well flowing conversations. And as long as you don't have any packet loss or large packet jitter, the sound will be very clear and clean because it is all-digital. I routinely see 300ms-350ms of latency and the customers don't seem to mind.

That being said, if you can get terrestrial, get it, for all the reasons you've laid out above.

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can afford the

This is a VOIP forum not a satellite telephony forum. :o

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This is not a forum - this is a newsgroup :-)

Reply to
Stefan Pfefferkorn

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