[Asterisk-Users] SIP / IAX over satellite

[Uriel Carrasquilla]

are you using Frame Relay? how big are the packets? I don't think you would
be using ATM over a satellite VSAT modem.  Also don't be fooled, satellite
modems don't speak IP.  There is normally an IP edge device that makes you
believe it is IP.
The 500 ms delay is the speed of light.  You need to add the time for the
protocols used by the satellite links.  On top of that, you have the delays
of IAX itself when it assembles the packets.
All in all, you might be experiencing delays closer to 800 ms or more if
VSAT modem is poorly configured.
The other question to ask is if you are fully duplex.  In the satellite
world you do need two independ up/down links.
IP over satellite is crazy.  By nature satellites are broadcasting. Voice
over satellite is already a challenge.  I have done IAX over satellite but
using small frame relay packets (256) and stopping any error retransmissions
on the satellite modems.  The result can be acceptable if you train your
users to the 1/2 second delay and the fact that two people cannot talk at
the same time (a challenge for us in South America).
Regards,
Uriel

-----Original Message-----
From: asterisk-users-admin at lists.digium.com
[mailto:asterisk-users-admin at lists.digium.com]On Behalf Of Tilghman
Lesher
Sent: Saturday, October 11, 2003 7:03 PM
To: asterisk-users at lists.digium.com
Subject: Re: [Asterisk-Users] SIP / IAX over satellite



On Saturday, Oct 11, 2003, at 17:04 America/Chicago, Paul Mahler wrote:

> Which satellite system?
>
> I think you need some specialized support, even special hardware.
> Check
> out
>
> http://www.groundcontrol.com/igvoip_001.htm
>
> You may need to replace TCP/IP
>
> http://www.mentat.com/skyx/skyx-gateway.html

I don't know why he'd need to replace TCP/IP when both SIP as well as
IAX use UDP/IP.  There may be substantial latency, however.

-Tilghman

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