[Asterisk-Users] FAX over PRI

[Craig Guy]

CPU load definitely affects rxfax - typical symptoms will be pages cut in 
half.  The effect is worse in Asterisk 1.2 than 1.0 - I have a perl agi 
running and on my test system (PIII 933mhz) the initialisation of the agi 
takes about 3 seconds.  On asterisk 1.2 the exact same agi on the same 
system takes 12 seconds and pegs the cpu at 100% the whole time.  People 
using festival have also noticed this issue to the extent that festival is 
unusable on lower end hardware for asterisk 1.2

Craig

----- Original Message ----- 
From: "Colin Anderson" <ColinA at landmarkmasterbuilder.com>
To: "'Asterisk Users Mailing List - Non-Commercial Discussion'" 
<asterisk-users at lists.digium.com>
Sent: Saturday, May 20, 2006 12:48 AM
Subject: RE: [Asterisk-Users] FAX over PRI


> My failure rate, objectively measured, is 3.8%, and this is with 100 - 400 
> a
> day. Other than clock slips (which definitely adversely affects fax) I 
> also
> note that load is an issue. A system with a higher load has a higher
> probability of failing the fax. Unfortunately, I don't have precise 
> numbers,
> as I have gotten a feel for this by watching 2 SSH windows to the same 
> box,
> 1 running top and the other running the Asterisk console.
>
>
>
> -----Original Message-----
> From: Noah Miller [mailto:noahisaacmiller at gmail.com]
> Sent: Friday, May 19, 2006 10:32 AM
> To: Asterisk Users Mailing List - Non-Commercial Discussion
> Subject: Re: [Asterisk-Users] FAX over PRI
>
>
> Hi Tom -
>
>> I have had nothing but problems receiving faxes over PRIs with spandsp. 
>> I
>> currently have 4 systems, 4 PRIs from 4 different providers... none of
> them
>> get better than 50% success rates receiving faxes in spandsp, I 
>> constantly
>> get cut off pages.  No body seems to have a fix for it, and it is really
>> frustrating.  Supposedly it is caused by "frame slips" on the PRI, but if
>> that is the case, I am 4 for 4 getting crappy PRIs that can't keep time.
>
> Just an aside thought (sorry to hijack the thread, Steve):
>
> 50% - Ouch.  I only have one PRI at one of our offices, but we use it
> to receive faxes that are directly sent via Digium FXS to an analog
> fax machine.  I've never formally tallied up the transmission errors,
> but we get something close to 100%.  Maybe spandsp is an issue here.
>
> - Noah
>
>
>
> On 5/19/06, Tom Christensen <tomsmaillists at gmail.com> wrote:
>> I have had nothing but problems receiving faxes over PRIs with spandsp. 
>> I
>> currently have 4 systems, 4 PRIs from 4 different providers... none of
> them
>> get better than 50% success rates receiving faxes in spandsp, I 
>> constantly
>> get cut off pages.  No body seems to have a fix for it, and it is really
>> frustrating.  Supposedly it is caused by "frame slips" on the PRI, but if
>> that is the case, I am 4 for 4 getting crappy PRIs that can't keep time.
>>
>> These same boxes work fine when receiving faxes over fxo ports, or if I
> plug
>> a fax machine into an fxs port and call in to a spandsp extension the fax
>> will be received just fine, so I am left thinking it must be the PRIs, 
>> but
>> if all PRIs are this bad, how can anybody be using them?
>>
>> Tom
>>
>>
>> On 5/19/06, Steve Hanselman <SteveH at brendata.co.uk> wrote:
>> > Sorry for the late reply but both of these are fine, we use spandsp to
>> > print some faxes and email others.
>> >
>> > We also route via a PRI to our other phone system to hylafax on an
>> > analog modem and also to an analog fax.
>> >
>> > So what you want to do is fine and will work.
>> >
>> > Steve
>> >
>> >
>> > -----Original Message-----
>> > From: asterisk-users-bounces at lists.digium.com
>> > [mailto: asterisk-users-bounces at lists.digium.com] On
>> Behalf Of Michael
>> > Gaudette
>> > Sent: 21 March 2006 20:34
>> > To: 'Asterisk Users Mailing List - Non-Commercial Discussion'
>> > Subject: RE: [Asterisk-Users] FAX over PRI
>> >
>> > Hmmm, Im not so sure I can apply this to me though.  I just want to do
>> > Fax-To-Email using PRI channels as the incoming lines.  Not so much
>> > transfer
>> > to a real fax.
>> >
>> > I am assuming that this is easily done with Asterisk? (I did it before
>> > with
>> > Asterisk SIP, but it only worked once every 10 tries or so)
>> >
>> > Mike
>> >
>> > -----Original Message-----
>> > From: asterisk-users-bounces at lists.digium.com
>> > [mailto:asterisk-users-bounces at lists.digium.com] On
>> Behalf Of Andrew
>> > Kohlsmith
>> > Sent: March 21, 2006 3:25 PM
>> > To: asterisk-users at lists.digium.com
>> > Subject: Re: [Asterisk-Users] FAX over PRI
>> >
>> > On Tuesday 21 March 2006 15:09, Michael Gaudette wrote:
>> > > How should I consider Fax over PRI channels with Asterisk?  Is the
>> > > quality and reliability good, or should I be prepared for alot of
>> > grief?
>> >
>> > I'm having good success doing fax over PRI using a TE405; one span to
>> > the
>> > PRI, the other to an FXS channel bank that is almost obscenely
>> > underutilized
>> > (3 channels).
>> >
>> > I also have channel bank - T100P - IAX2 - TE405 - PRI, where the IAX2
>> > link
>> > is a 1-hop SDSL (VOIP only) data link.  This works well too.
>> >
>> > -A.
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