Re: [asterisk-dev] Routing data modem calls
It's not binded with Asterisk, but I'm behind a satellite connection, and regullar faxes works - but with CISCO equipment... On 28 July 2006 20:23, John Lange wrote: On Fri, 2006-07-28 at 09:08 -0400, Andrew Kohlsmith wrote: Faxes are more of a problem because their lower-end connection rate is typically 9600 baud. Although some will train down (Mr. Underwood would be the authoritative source on these terms and implementation) to 2400 or even 1200 baud, I have not seen this much in practice. Just recently I had a satellite vendor tell me that he was able to get faxing to work over VoIP on satellite. I found that very hard to believe. However, he told me a local fax machine specialist (he really _really_ knows his fax machines) was able to tune certain higher end fax machines so they would work reliably even in these extreme circumstances. I'm certainly not convinced this is true but if anyone is interested I could do some more leg work and see what I can find out. John ___ --Bandwidth and Colocation provided by Easynews.com -- asterisk-dev mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-dev ___ --Bandwidth and Colocation provided by Easynews.com -- asterisk-dev mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-dev
Re: [asterisk-dev] Routing data modem calls
Hi, In many cases, I noticed (though I didn't experienced) data modems could simply be replaced by serial-to-ethernet converters plus dialup routers. What do you think of that ? Regards ___ --Bandwidth and Colocation provided by Easynews.com -- asterisk-dev mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-dev
Re: [asterisk-dev] Routing data modem calls
On Fri, Jul 28, 2006 at 12:49:14PM +0200, Olivier Krief wrote: In many cases, I noticed (though I didn't experienced) data modems could simply be replaced by serial-to-ethernet converters plus dialup routers. What do you think of that ? That won't work for me: (1) EPOS terminals may have modems built-in. It would require modifications to the terminals to get at the RS232 signals. (2) The other end (i.e. the bank or whatever) would also need to install serial-to-ethernet convertors, in addition to their existing modem bank. Then I would need to install a secure IP link into the bank or whatever, whereas at the moment all these calls just come in over the PSTN. Regards, Brian. ___ --Bandwidth and Colocation provided by Easynews.com -- asterisk-dev mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-dev
Re: [asterisk-dev] Routing data modem calls
On Friday 28 July 2006 05:27, Brian Candler wrote: Furthermore, a G.711 call uses a large bandwidth (up to ~120kbps), even for a low data rate modem, or when no data is being transmitted. A typical ADSL line has an uplink capacity of 288kbps, so 2 calls would eat all that up. ?? Most ADSL lines around here (southwestern Ontario, Canada) are 800kbps up, but yes, we can get pretty low depending on distance from CO. My home, for example, has an uplink of 512kbps. Also, a ulaw audio stream in RTP is about 80kbps. Of course that is 80kbps upstream, 80kbps downstream, but you don't get to add them together and say it's 160kbps (or 120kbps in your example). 4. V.42 error correction is implemented using HDLC frames. If there was an RTP payload type for carrying HDLC frames, these could be exchanged end-to-end. It would have the advantage of performing end-to-end error correction, data compression and flow control between the endpoint modems, without the intervening network having to get involved. This would be nifty. I've also noted that most POS terminals use 2400 baud since there is no channel equalization or excessive training performed and this keeps call length to a bare minimum. (Useful because they typically dial some 800# and the POS vendor likely has 1/1 billing on their 800 line.) I've not noticed much trouble with 2400-baud modem connections over stable IP networks, but then again I'm not willing to say it will always work, either. :-) Faxes are more of a problem because their lower-end connection rate is typically 9600 baud. Although some will train down (Mr. Underwood would be the authoritative source on these terms and implementation) to 2400 or even 1200 baud, I have not seen this much in practice. These points aside, you have put a lot of thought into this and I hope some decent conversation and even feasible goals come out of this. I'll be watching this thread carefully. :-) -A. ___ --Bandwidth and Colocation provided by Easynews.com -- asterisk-dev mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-dev
Re: [asterisk-dev] Routing data modem calls
- Original Message - From: Brian Candler [EMAIL PROTECTED] To: Olivier Krief [EMAIL PROTECTED] Cc: asterisk-dev@lists.digium.com Sent: Friday, July 28, 2006 3:05 PM Subject: Re: [asterisk-dev] Routing data modem calls On Fri, Jul 28, 2006 at 12:49:14PM +0200, Olivier Krief wrote: In many cases, I noticed (though I didn't experienced) data modems could simply be replaced by serial-to-ethernet converters plus dialup routers. What do you think of that ? That won't work for me: (1) EPOS terminals may have modems built-in. It would require modifications to the terminals to get at the RS232 signals. I totally agree with you : if you have a built-in modem and no way to use another communication port (which obviously could be the case with some terminals), you have find a way to transport modem signals. (2) The other end (i.e. the bank or whatever) would also need to install serial-to-ethernet convertors, in addition to their existing modem bank. Then I would need to install a secure IP link into the bank or whatever, whereas at the moment all these calls just come in over the PSTN. I was thinking of this case : Instead of : Terminal --- Data Modem PBX PSTN -Modem Bank Whatever Use this : Terminal --- Serial-to-Ethernet LAN Dialup router PSTN Modem Bank Whatever In the latter situation, you can concentrate several terminals spread on different locations with a single router (and then cut several TDM lines to PSTN). And when the other side (i.e. the bank or whatever) moves to IP, changing the router is enough. I met this case with legacy Payment Terminals which have a built-in serial port and a FXO port while new ones (and high end) now have a built-in Ethernet port. Regards, Brian. ___ --Bandwidth and Colocation provided by Easynews.com -- asterisk-dev mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-dev
