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Summary:ASTERISK-22842: V29 is incompatible with minrate setting 2400
Reporter:Thomas Rechberger (ghost75)Labels:
Date Opened:2013-11-12 08:15:23.000-0600Date Closed:2014-12-12 09:26:39.000-0600
Priority:TrivialRegression?
Status:Closed/CompleteComponents:Resources/res_fax
Versions:1.8.14.0 Frequency of
Occurrence
Related
Issues:
causesASTERISK-25001 SendFAX error
is related toASTERISK-23231 Since 405693 If we have res_fax.conf file set to minrate=2400, then res_fax refuse to load
is related toASTERISK-22790 check_modem_rate() may return incorrect rate for V.27
Environment:WheezyAttachments:
Description:Get the following error:
ERROR[8432]: res_fax.c:2086 sendfax_exec: 'modems' setting 'V29' is incompatible with 'minrate' setting 2400

I am using default options in res_fax.conf:
minrate = 2400
modems = V17,V27,V29

When i put in dialplan FAXOPT(modem)=V29 to force using V29 (because V17 is not able to send with 9600baud), then i get the error above. Does this mean if the default order is V17,V27,V29 then V29 can never be used because the min bitrate is always to low?
And why is V29 then not using bounds of maxrate?
Comments:By: Matt Jordan (mjordan) 2013-11-12 09:16:02.314-0600

A quick google:

{quote}
V.29 Fax modem software (V29 fax softmodem)

GAO V.29 fax modem software implements the ITU-T V.29 Recommendation, which provides full-duplex data transmission at rates of 9600, 7200, and 4800bps over 4-wire leased lines. GAO's V29 modem data pump software has "quick connect" feature. It is also the modulation technique used in Group 3 fax (G3 fax) for fax data transfer at 9600bps and 7200bps on 2-wire lines. It consists of transmitting functions and receiving functions which are called to transmit/receive bits in groups of 2 or 3 (referred to as symbols) at rates of 1200 or 1600 symbols per second respectively. More
{quote}

So no, a bit rate of 2400 is not allowed for that rate. The minrate specified in the configuration file is a 'global' minimum rate for all modems; that doesn't mean that it will be chosen for a specific modem.

By: Thomas Rechberger (ghost75) 2013-11-12 10:30:40.595-0600

In my case it was chosen if v29 was forced and faxing didnt work until i defined minrate = 9600. Or is the minrate not any more "global" as soon there is only one fax modem specified?
By: Joshua C. Colp (jcolp) 2013-11-12 11:30:51.277-0600

<ghost75> file: but then the default modem order v17,v27,v29 doesnt make sense because minrate 2400 is specified as default
<ghost75> and also v17 doesnt allow 2400 baud
By: not here (looserouting) 2014-10-07 10:54:13.342-0500

I am not 100% sure but it seems that it doens't makes sense to check the minrate at that point/state at least.

I agree that minrate=2400 cannot be used because none of the selected modems support that rate. But res_fax should select/use the next possible higher rate when communicating to the remote fax machine.

I didn't check how res_fax selects the rate in a fax call, but this could simplify the code and help the users.
If you take a lot how a normal user will lokk at this... since 2400  < 9600 why should't it work.

By: Matt Jordan (mjordan) 2014-12-12 09:26:39.225-0600

I'm closing this out as "Fixed", as the {{minrate}} was changed to 4800 in ASTERISK-23231, a WARNING was introduced if you have incompatible {{modem}}/{{minrate}} settings, and the {{minrate}} is bumped to 4800 if if you have an incompatible setting.