Re: [Asterisk-Users] T.38 fax summary
Hi, my name is Pedro Caria I'm new to this list. I live in Portugal and find myself in the position to talk often to various parts of the world, very often the Telco line has a delay superior to 1s, I also fax in the same conditions, so to my experience faxes do work with delays far superior to 75ms. Am I missing something ? Pedro Caria On 27/fev/2005, at 17:10, Lee Howard wrote: On 2005.02.27 08:34 Martijn van Oosterhout wrote: Hi, I read it and found it very enlightening. I do have one question regarding Modems don't like relativity. It says modems need a constant delay; is there a limit to what it can handle. For example, would it be possible to configure a jitterbuffer right at the endpoint before the fax to put a constant delay of 1 second relative to the sender. This should be enough time to weed out any jitter. Basically, fix the jitterbuffer so the delay is constant. If a fax can handle a constant delay of up to a second you're home. Fax cannot handle a one-second delay. As Steve mentions in the article, per-spec fax has some timings (particularly silence in direction switching) set at 75 ms +/- 20 ms. So if the delay gets much larger than 75 ms, then there's likely to be trouble. Now, some fax machines may tolerate larger delays, but that tolerance is beyond the spec, and thus should not be used as a gauge. Lee. ___ Asterisk-Users mailing list Asterisk-Users@lists.digium.com http://lists.digium.com/mailman/listinfo/asterisk-users To UNSUBSCRIBE or update options visit: 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 To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
Re: [Asterisk-Users] Clarification on Fax capability?
I've been trying this for a while and I have been unable to get a reliable connection betwen two Zaptel FXS interfaces, so the bridging does afect data transfer. Anybody got some tunning tips to get this to work ? I'm using a dual PIII with a ServerWorks Chipset, two TDM cards (8xFXS) and a Fritz Capi to connect to my telecom provider. I can send faxes with some success, but receiving rate of success is less than 30%. Fax information for Asterisk is difficult to come by is everybody using spandsp's way ? Thx Pedro Caria On 15/fev/2005, at 15:05, Rich Adamson wrote: On Tue, February 15, 2005 7:48 am, Rich Adamson said: 2) simply switching a fax call through * to a tip/ring interface of some sort that has an attached traditional fax machine. Does the codec issue with #2 still apply if the incoming fax call is on a Zaptel FXO interface? Is the codec used when connecting two channels on the same zaptel card or does the native bridg[ing] bypass that? Funny that you should ask. I just finished testing it using the faxdetect=incoming method, redirecting the call to a Cisco ata186. The incoming call arrived on a TDM fxo port. Received the fax header, but the remainder of the page was blank. The sender received a message indicating a failure. Best guess... the tdm driver problem is impacting the ability to send the fax tones reliably even with g711. Its very likely to be the interrupt latency and/or pci bus problem on this particular system. ___ Asterisk-Users mailing list Asterisk-Users@lists.digium.com http://lists.digium.com/mailman/listinfo/asterisk-users To UNSUBSCRIBE or update options visit: 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 To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
