[asterisk-users] how to set iaxmodem receiving speed

[Tim Nelson]

----- Original Message -----
> Hi guys, thanks for answers.
> 
> That could seem counter-intuitive but it is not. Not to mention the
> fact
> that information technology is not science, 

Huh? It is indeed very much a science. You have known established facts, processes, concepts, methods for testing and implementing those elements.

> the solution to broken faxes
> is to lower down speed. This works even with normal telco lines even

*Sometimes* lowering speeds can help get faxes through, but you're missing the big picture. Fax is sensitive to latency, jitter, timing, interference, audio clipping, etc. Simply lowering your speed will not magically make all of those issues go away. You need to be looking at finding a solution to the root cause of the problem, not throwing some odd ideas at the symptoms.

> if
> you DO NOT have a pbx (telco technicians even say not to make faxes
> pass
> thru your PBX). I could ask my customer's telco to lower the speed
> down

How would the telco lower the speed of your customer's fax gear? Unless they have direct control of it, or are providing some sort of T.38<->T.30 service, the only way I can think of is they would have to introduce a problem on the line that would force the fax sender/receiver to force a lower speed during normal negotiation. Someone please correct me if I'm wrong?

> but it depends on the guy working at the call-center...sometime you
> talk
> to dummy people who ARE sure it is impossible. But it is not. So, I
> do
> not want to spend days to convince people working at that telco
> call-center that what I'm asking is feasible and I do not want to
> tell
> my customer to tell their customer to lower their faxes speed (before
> installing our PBX they were able to send perfect faxes so, why
> should
> they?).

Again, your PBX/equipment/whatever can be 100% the best, most reliable system ever to be installed. BUT, if you have senders that are on poor lines, running over VoIP, or have a multitude of other issues, the problem lies with them. There is not much you can do to solve this.

> 
> My idea was to tell iaxmodem not to accept fast speed rates so the
> fax
> machine on the other side should be forced to negotiate a slower
> speed
> as if my customer fax weren't virtual as iaxmodem is but a real one.
> 
> I suspect that the problem is about the primary lines because I
> tested
> iaxmodem many times on my LAN and it is (surprisingly :) ) working
> fine

Yes, performance *can* be good on an unloaded LAN. But again, it is fax over VoIP which means tomorrow it may not work because Jim Bob over in accounting is updating Windows, watching Youtube, downloading some music via Bittorrent, and backing up his machine to the fileserver. Point being, network performance is 100% responsible for your local IAXmodem experience over the LAN. :)

> (10 good received faxes out of 10 sent!!!) but, as you may know,
> talking
> to telco technician is a nightmare....they always say problems are
> always on the PBX side... :(

I'm sure that is standard procedure. If you were in their shoes, would you want to deal with every possible PBX issue that comes around? I'm not saying it's right, just that's the way it is. 

> 
> Moreover, after sending a fax, the fax machine beeps correctly as the
> fax was correctly sent without corruption. :o

No, the fax machine beeps to say the fax was *SENT*. Whether or not there was any corruption is entirely up to the sender/receiver to determine, typically with copy quality checking or ECM.

> 
> I hope I have made my point but I'll try do dig deeper inside the
> problem as you suggested me.
> 

A point was indeed made.

--Tim