I have pretty good luck faxing through the Adtran TotalAccess series devices.. These devices do provide positive disconnect on their analog lines. plus they are a full featured device that I use for multiple purposes on each site..
They are a bit tricky to get working with asterisk but they do work great once you get them set up. you can set a straight modem passthrough mode which it detects and alters the codecs, echo cancellers, etc for pretty reliable transmission without using T.38. or you can use T.38 weith pretty good success. The biggest issues with T.38 come down to the timing delays and issues with multiple network hops.. esp if somewhere along the lines a T.38 aware device in between decodes the T.38 and re-encodes it.. you are done then.. -Christopher From: James Babiak [mailto:[email protected]] Sent: Friday, May 28, 2010 8:38 AM To: AstLinux Users Mailing List Subject: Re: [Astlinux-users] Faxing To throw in my two cents, we've used SPA3102s that would register directly to a remote 'fax' server using T.38 with limited success. Seems like the majority of fax machines would work the majority of time, but only on short faxes (less then a few pages). The more pages you sent, the failure rate went up dramatically. We then looked at AudioCodes devices. The MP2XX series proved to be much more stable then the SPAs. On the SPAs, we had to make changes on most fax machines (disable ECM, lower speed to 14.4kbps or less) that we did not need to make on the AC. In addition, certain fax machines that we could never get working on the SPAs worked great without any tweaks on the ACs. So we're using the MP201,202,204 and even 208 for fax ATAs now. My only pet peeve is that they do not provide any CPC loop disconnect. Even the Crapstream ATAs would do this. All they can do is play a tone that defaults to a fast busy but is user selectable. Has caused problems with a few PBX systems. AudioCodes says they are working on a firmware fix for this as the hardware supports it. Until that time, we are looking at the better, albeit more expensive, 100 series which provides it out of the box. Personally, I've tested out faxes using an old Sunrocket ATA and G711, and actually had some limited success with that as well. -James Tod Fitch wrote: If your VoIP provider is setup for T.38 then you may have an issue. For in-bound faxes you are in control: If you don't allow T.38 then it will stay with whatever codec you have negotiated. Which should be g711. For out-bound faxes you are at the mercy of your VoIP provider's setup. The receiving (provider's) side of the VoIP connection can detect that a fax is being sent and attempt a re-invite using T.38. The PAP2T does not support T.38. I switched to using a Grandstream HT502 which claims support for T.38 but still haven't gotten it to work through my Astlinux box. My provider claims better operation if you have the ATA directly register with them. The Asterisk logging with debug on claims a rejected codec but I don't know if that is Asterisk complaining or if it is my ATA. I haven't yet bothered looking at the traffic with Wireshark to figure out exactly what is going on. Net result: If your provider does not do T.38 then you can probably get faxes to work using the g711 codec. I have maybe a 95% fax success rate with that type of operation. Not good enough for a heavy business use but good enough for my needs. If the provider re-invites to T.38 then you may have a 0% success rate (my experience). I believe that the specs call for graceful fall back to the voice codec if the T.38 invite fails but I haven't seen that happen (two different VoIP providers). If anyone knows how to get this to work I would dearly like to know. -Tod On May 27, 2010, at 6:34 AM, David Kerr wrote: I should add that the PAP2T I have is one that I got through Nextalarm.com which is customized to support alarm/security system monitoring over the internet (VoIP). The ATA is customized to connect one of the analog lines into their systems, the other line is available to configure for my own use (after you get the admin password from them). I mention this because it is possible that the customization included work to improve the A to D conversion process, not just hard wiring one of the lines to nextalarm's systems... https://nextalarm.com/do/customer/productDetail?id=17 David On Thu, May 27, 2010 at 9:28 AM, David Kerr <[email protected]> wrote: The answer is "it depends." I have had success with a fax machine connected to a linksys PAP2T ATA and routing through vitelity as the SIP trunk provider (with Astlinux in-between). I have had complete failure with an older Linksys/Sipura SPA-2002 and the same SIP trunk. I have both a PAP2T and SPA-2002 connected to my system and the audio quality is noticeably better on the PAP2T. In particular there is a lot of background hiss from the SPA-2002 that is not present on the PAP2T. That may also suggest that the dynamic range of the SPA-2002 is not as strong as the PAP2T. Both the background hiss and a compressed dynamic range would explain why analog fax does not work well. In addition to good A to D conversion, which the PAP2T seems to handle well, you then have to deal with the characteristics of SIP/VoIP. You may have to fiddle with settings like jitter buffer and echo cancelling and you want a high quality trunk provider. Good luck. David On Thu, May 27, 2010 at 8:17 AM, Tom Chadwin <[email protected]> wrote: Slightly OT... With an uncustomized 0.7.2 (1.4) on a net5501 with a berofix PRI, what is the easiest way to attach an analogue fax which currently uses one DDI on the UK PRI? Will an ATA work? Thanks Tom _____ ---------------------------------------------------------------------------- -- _____ _______________________________________________ Astlinux-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/astlinux-users Donations to support AstLinux are graciously accepted via PayPal to [email protected].
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