Hi all, For some reason VSAT or Satellite Internet services are not mentioned (or searchable) in this list's archives. I thought I'd let you know that I tested Asterisk using IAX (not IAX2) to make a phone call from an analog phone hooked up to an Asterisk system behind a Linksys router connected to a Gilat VSAT satmodem, and it worked. The "other end" (gateway) is a P200MMX with a X100P FXO card. I have bi-directional calling set up so that the VSAT-phone can make outbound calls using the X100P in the gateway, and if the X100P gets a ring it answers and transfers the call to the analog phone on the other side of the VSAT. There is about a 1-2 second propagation delay in voice from the VSAT phone, as expected. The echo is not bad at all, and the voice quality is quite good. I don't think the VSAT network was very busy so I don't know how well this will work if the available bandwidth is less. We are not using the G.729 codec - just gsm. I have tos=reliable set in iax.conf. I didn't get disconnected during my test calls, but they weren't very long in duration. I haven't tried a fax but maybe I will. Anyway congratulations Mark et al on your fine work making such a robust VoIP system. Thanks! -- Jim Ockers, P.Eng. (ockers@ockers.net) Contact info: please see http://www.ockers.net/
What bandwidth do you have available for you connection (upsteram and downstream)? Do you have any CIR for VSAT connection ? Martin On Thu, 29 May 2003, Jim Ockers wrote:> Hi all, > > For some reason VSAT or Satellite Internet services are not mentioned > (or searchable) in this list's archives. I thought I'd let you know > that I tested Asterisk using IAX (not IAX2) to make a phone call from > an analog phone hooked up to an Asterisk system behind a Linksys router > connected to a Gilat VSAT satmodem, and it worked. > > The "other end" (gateway) is a P200MMX with a X100P FXO card. I have > bi-directional calling set up so that the VSAT-phone can make outbound > calls using the X100P in the gateway, and if the X100P gets a ring it > answers and transfers the call to the analog phone on the other side > of the VSAT. > > There is about a 1-2 second propagation delay in voice from the VSAT > phone, as expected. The echo is not bad at all, and the voice quality > is quite good. > > I don't think the VSAT network was very busy so I don't know how well > this will work if the available bandwidth is less. We are not using the > G.729 codec - just gsm. I have tos=reliable set in iax.conf. I didn't > get disconnected during my test calls, but they weren't very long in > duration. > > I haven't tried a fax but maybe I will. > > Anyway congratulations Mark et al on your fine work making such a robust > VoIP system. Thanks! > > -- > Jim Ockers, P.Eng. (ockers@ockers.net) > Contact info: please see http://www.ockers.net/ > _______________________________________________ > Asterisk-Users mailing list > Asterisk-Users@lists.digium.com > http://lists.digium.com/mailman/listinfo/asterisk-users >
Hey Jim, All sounds good. We tried a satellite system here a few months ago but couldn't get on with it. Glad you've had more success. In theory, it shouldn't matter whether the TCP/IP link between your sites is going over satellite, modem or any other medium but the issues we found with satellite that would be particularly damaging for VoIP were as follows: - Latency. You're onto this one already by the sounds of it. We were seeing 750ms pings so you're looking at delays of around 1 second; 1.5-2 seconds for someone to hear what you've said and reply. That doesn't prevent a conversation but might make it sound a little strange to the other party who doesn't know what is going on. - Upstream. We had a system with 2Mbps downstream but since the upstream is the expensive part for providers to provide it is usually much much smaller - ours was only 128k. That is one call for many codecs without allowing for any other use you'll be making of the line. G.729 would improve this a lot as you've spotted. - Drop-outs. A satellite system should theoretically provide continuous service like a leased line or modem connection so you shouldn't get call dropouts. However, we found that we'd lose all connectivity from our provider for several seconds at a time. It could have been a peculiarity of the way they were prioritising traffic, routing, excessive contention or even the non-TCP/IP method for the dish<>sat<>dish part of the link but it seems whenever other customers were making heavy downloads others would slow down to just a few bps or drop out completely. That wouldn't be good for the quality of any calls in progress even if the connection was maintained. I'm not meaning to be negative or dash your enthusiasm but if I had a choice of links to do VoIP over, satellite would be at the bottom, even below modems. Our experience could be unique of course and if you own both ends of the link then you have far more control over the issues I've mentioned, other than latency of course. All the best, Simon ----- Original Message ----- From: "Jim Ockers" <ockers@ockers.net> To: <asterisk-users@lists.digium.com> Sent: Thursday, May 29, 2003 7:47 PM Subject: [Asterisk-Users] Asterisk IAX over VSAT satellite.> Hi all, > > For some reason VSAT or Satellite Internet services are not mentioned > (or searchable) in this list's archives. I thought I'd let you know > that I tested Asterisk using IAX (not IAX2) to make a phone call from > an analog phone hooked up to an Asterisk system behind a Linksys router > connected to a Gilat VSAT satmodem, and it worked. > > The "other end" (gateway) is a P200MMX with a X100P FXO card. I have > bi-directional calling set up so that the VSAT-phone can make outbound > calls using the X100P in the gateway, and if the X100P gets a ring it > answers and transfers the call to the analog phone on the other side > of the VSAT. > > There is about a 1-2 second propagation delay in voice from the VSAT > phone, as expected. The echo is not bad at all, and the voice quality > is quite good. > > I don't think the VSAT network was very busy so I don't know how well > this will work if the available bandwidth is less. We are not using the > G.729 codec - just gsm. I have tos=reliable set in iax.conf. I didn't > get disconnected during my test calls, but they weren't very long in > duration. > > I haven't tried a fax but maybe I will. > > Anyway congratulations Mark et al on your fine work making such a robust > VoIP system. Thanks! > > -- > Jim Ockers, P.Eng. (ockers@ockers.net) > Contact info: please see http://www.ockers.net/ > _______________________________________________ > Asterisk-Users mailing list > Asterisk-Users@lists.digium.com > http://lists.digium.com/mailman/listinfo/asterisk-users >
Martin,> What bandwidth do you have available for you connection (upstream and > downstream)? Do you have any CIR for VSAT connection ?I think we have 400Kbps downstream and 56-112Kbps upstream. No CIR that I know of, it's first come first served for the bandwidth, and it's all shared all the time as far as I know. However it's pretty good "broadband" service and definitely usable for interactive stuff like webex or ssh, so I guess I shouldn't be surprised that it works OK for VoIP as well. -- Jim Ockers, P.Eng. (ockers@ockers.net) Contact info: please see http://www.ockers.net/
Remember that a ping is round trip so the other user should only experience a 325ms delay on a 650ms circuit. What you would be expieriecing is the overlap in conversations as a result of the delay. i.e. when someone stops talking, it takes about 300ms for the other side to start getting the pause and then 300 more ms for the persons responce to get back to the original speaker. While there are many other pitfalls to VoIP and TCP-IP over satellite (I can expond on many of them as I work for a company in the buisiness) it still is a viable option in many situations. Mobile sites, remote locations, maritime, quick responce and many other unique situations make satellite a very viable option for many users. As far as dropouts are concerned, a well designed satellite system can operate at 99.995% availability or more. For licencing concerns, Ku is prefered over C. Most systems sold as consumer systems are also sharing bandwidth which would cause some additional concerns for the importance of the data being transported. (I can expound if anyone is interested.) I have a testbed up here constantly and can go for about a month before noticing any downtime. Chad C. Wicker Systems Engineer Petrocom>>> woodheads@gonegardening.com 5/29/2003 2:39:16 PM >>>Hey Jim, All sounds good. We tried a satellite system here a few months ago but couldn't get on with it. Glad you've had more success. In theory, it shouldn't matter whether the TCP/IP link between your sites is going over satellite, modem or any other medium but the issues we found with satellite that would be particularly damaging for VoIP were as follows: - Latency. You're onto this one already by the sounds of it. We were seeing 750ms pings so you're looking at delays of around 1 second; 1.5-2 seconds for someone to hear what you've said and reply. That doesn't prevent a conversation but might make it sound a little strange to the other party who doesn't know what is going on. - Upstream. We had a system with 2Mbps downstream but since the upstream is the expensive part for providers to provide it is usually much much smaller - ours was only 128k. That is one call for many codecs without allowing for any other use you'll be making of the line. G.729 would improve this a lot as you've spotted. - Drop-outs. A satellite system should theoretically provide continuous service like a leased line or modem connection so you shouldn't get call dropouts. However, we found that we'd lose all connectivity from our provider for several seconds at a time. It could have been a peculiarity of the way they were prioritising traffic, routing, excessive contention or even the non-TCP/IP method for the dish<>sat<>dish part of the link but it seems whenever other customers were making heavy downloads others would slow down to just a few bps or drop out completely. That wouldn't be good for the quality of any calls in progress even if the connection was maintained. I'm not meaning to be negative or dash your enthusiasm but if I had a choice of links to do VoIP over, satellite would be at the bottom, even below modems. Our experience could be unique of course and if you own both ends of the link then you have far more control over the issues I've mentioned, other than latency of course. All the best, Simon ----- Original Message ----- From: "Jim Ockers" <ockers@ockers.net> To: <asterisk-users@lists.digium.com> Sent: Thursday, May 29, 2003 7:47 PM Subject: [Asterisk-Users] Asterisk IAX over VSAT satellite.> Hi all, > > For some reason VSAT or Satellite Internet services are notmentioned> (or searchable) in this list's archives. I thought I'd let you know > that I tested Asterisk using IAX (not IAX2) to make a phone callfrom> an analog phone hooked up to an Asterisk system behind a Linksysrouter> connected to a Gilat VSAT satmodem, and it worked. > > The "other end" (gateway) is a P200MMX with a X100P FXO card. Ihave> bi-directional calling set up so that the VSAT-phone can makeoutbound> calls using the X100P in the gateway, and if the X100P gets a ringit> answers and transfers the call to the analog phone on the other side > of the VSAT. > > There is about a 1-2 second propagation delay in voice from the VSAT > phone, as expected. The echo is not bad at all, and the voicequality> is quite good. > > I don't think the VSAT network was very busy so I don't know howwell> this will work if the available bandwidth is less. We are not usingthe> G.729 codec - just gsm. I have tos=reliable set in iax.conf. Ididn't> get disconnected during my test calls, but they weren't very long in > duration. > > I haven't tried a fax but maybe I will. > > Anyway congratulations Mark et al on your fine work making such arobust> VoIP system. Thanks! > > -- > Jim Ockers, P.Eng. (ockers@ockers.net) > Contact info: please see http://www.ockers.net/ > _______________________________________________ > Asterisk-Users mailing list > Asterisk-Users@lists.digium.com > http://lists.digium.com/mailman/listinfo/asterisk-users >_______________________________________________ Asterisk-Users mailing list Asterisk-Users@lists.digium.com http://lists.digium.com/mailman/listinfo/asterisk-users