[asterisk-users] how to set iaxmodem receiving speed

[gincantalupo]

Hi Steve,

you are telling me there is no way to set a particular speed on my 
iaxmodem in order to force the sender speed?
I have some problems with a customer who gets malformed faxes even if no 
error occurs. Since I cannot tell the sender to lower its fax speed, my 
idea is to force my iaxmodem to a lower fixed speed so the sender is 
oblidged to negotiate at that speed (or lower, of course) without the 
customer could realize it, at least at first. :)
There is no ATA in the middle (I'm using it for my tests but my customer 
does not have any), all faxes are received thru a primary channel to a 
bunch of iaxmodems. Sometimes some faxes are corrupted, that's why I 
thought to lower the speed. I could try to disable ECM but that's even 
harder to do (found nothing on internet).

Thank you

Giorgio


On 05/16/2012 07:24 PM, Steve Underwood wrote:
> Hi,
>
> On 05/16/2012 09:59 PM, Larry Moore wrote:
>> Read the subject line more closely.
>>
>> Tested receiving too,
>>
>> I set the Send & Receive speed of the receiving analogue modem to 
>> that below, the log file on the sending modem (iaxmodem) reported it 
>> capable of 9600.
>>
>> May 16 21:32:04.28: [ 2335]: REMOTE best rate 9600 bit/s
>> May 16 21:32:04.28: [ 2335]: REMOTE max A3 page width (303 mm)
>> May 16 21:32:04.28: [ 2335]: REMOTE max unlimited page length
>> May 16 21:32:04.28: [ 2335]: REMOTE best vres R16 x 15.4 line/mm
>> May 16 21:32:04.28: [ 2335]: REMOTE format support: MH, MR, MMR
>> May 16 21:32:04.28: [ 2335]: REMOTE supports T.30 Annex A, 256-byte ECM
>> May 16 21:32:04.28: [ 2335]: REMOTE best 0 ms/scanline
>> May 16 21:32:04.28: [ 2335]: USE 9600 bit/s
>>
>> Perhaps the issue is with Hylafax.
>>
>> Setting the Transmit & Receive strings to "!24,48,72,96" seems to 
>> yield the most reliability in transmission
> If you have an ATA in the path that is often the case. Many of them 
> badly mess up a FAX signal. Without such a distortion machine V.17 
> should be fine.
>>
>> Cheers,
>>
>> Larry.
>>
>> On 16/05/2012 7:23 PM, Larry Moore wrote:
>>> I have iaxmodem version 1.2.0 installed on my system.
>>>
>>> I have set the following in the IAX configuration file, SIGHUP'd 
>>> FaxGetty and submitted a single page outbound fax via Asterisk;
>>>
>>> Class1RMQueryCmd:       "!24,48,72"     # enable this to disable 
>>> V.17 receiving
>>> Class1TMQueryCmd:       "!24,48,72"     # enable this to disable 
>>> V.17 sending
>>>
>>> The resulting output from my T.38 Gateway reports the following;
>>>
>>>     -- Connection Statistics
>>>         Bit Rate :7200
>>>         ECM : No
>>>         Pages : 1
>>>     -- Hungup 'IAX2/iaxmodem0-11055'
>>>
>>> I also tested with the maximum speed set to 4800, the image was 
>>> received however the responses to EOP timed out, I don't know if the 
>>> is to do with my Asterisk T.38 gateway or my VoIP providers T.38 
>>> gateway. The result was the fax was retried for the defined number 
>>> of attempts.
>>>
>>> Cheers,
>>>
>>> Larry.
>>>
>>> On 16/05/2012 6:28 PM, gincantalupo wrote:
>>>> Hi all,
>>>>
>>>> I'm trying to lower my iaxmodem speed but still I haven't found any 
>>>> solution...I tried to add
>>>> Class1RMQueryCmd:       "!24,48,72"
>>>> to config.IAXtty but does not work...Hylafax says it it running at 
>>>> 9600 (sometimes at 14400) baud..
> This is correct behaviour. The sending side has fine control over the 
> modem modes it uses. The receiving side can only specify that V.27ter, 
> or V.27ter+V.29 or V.27ter+V.29+V.17 are OK. So, if you allow the 
> 7200bps mode of V.29 you are compelled to allows the 9600bps mode too.
>
> Steve
>
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