[Freeswitch-users] dtmf problem

Tim Bock jtbock at synacktics.com
Fri Jan 18 01:15:36 MSK 2013


Hi,

Thought I would update this for list posterity.

Although the spandsp_start_dtmf trick seemed to work for me, I soon 
discovered that I now had an echo problem, previously banished with 
oslec.  Indeed, lsmod still showed that oslec was loaded, and dahdi_cfg 
claimed that it was enabled for the channels in question. But when I 
would make or receive calls through the tdm card, I would not see the 
output of "cat /proc/dahdi/1" change.  It remained "OSLEC - INACTIVE."

I also began poring through the logs (past and present), and soon 
realized that freetdm does start a software dtmf detector (and in fact 
this had worked in the past).  So, there was something else going on.

I was trying various things, and looking through the list and docs, when 
(seemingly) all of a sudden, the echo went away and now the dtmf was 
detecting two keypresses for every single keypress.  Ok, sure, 
understandable since I had turned on spandsp_dtmf in addition to 
freetdm's dtmf detector, but why now?  And why did the echo magically 
disappear?

Eventually, I figured out that it was related to me 
connecting/disconnecting the fxo port, which I do since I'm using my 
home line for testing.  Something (freetdm or dahdi, presumably) doesn't 
like that.  What fixes it is to have the trunk line connected when the 
freeswitch server is rebooted.  There is undoubtedly a "smaller hammer" 
solution, but I haven't figured it out yet.  Just stopping and 
restarting freeswitch doesn't do it.

The upshot is that I removed the spandsp_start_dtmf from my dialplan.  
Rebooting with the trunk port occupied fixed all of the sins.

Tim

On 01/15/2013 12:39 PM, Tim Bock wrote:
> I can tell you how I solved the problem I was having.  Don't know if 
> this is preferred, or if there is a better way, but I'm now able to 
> detect dtmf from all sources (pstn, cell, sip).
>
> Apparently, mod spandsp has better dtmf detection than the dtmf 
> detection in the freeswitch core.  On the wiki page for spandsp 
> (http://wiki.freeswitch.org/wiki/Mod_spandsp), there is a section on 
> dtmf.  I added the spandsp_start_dtmf parameter before calling the 
> ivr, and that fixed my issue.
>
> Hope this helps,
> Tim
>
> On 01/15/2013 09:02 AM, Viacheslav Dubrovskyi wrote:
>> 14.01.2013 06:39, Tim Bock ?????:
>>> I have a freeswitch server with a digium tdm wildcard.  Compiled,
>>> enabled, and configured freetdm and dahdi...all seems to be working fine
>>> (can make/receive calls).
>>>
>>> My problem is with dtmf.  When calling from an external pstn number to
>>> freeswitch, dtmf seems to be detected properly and consistently. But
>>> when calling from a cell phone or via another voip line, dtmf doesn't
>>> seem to be detected, or detected only occasionally.
>>>
>>> On the same system, if I call into the voip number, calls from any of
>>> the three external options (landline, cell, sip) all seem to work fine
>>> with dtmf.
>>>
>>> So the problem seems to be something I've misconfigured with the tdm
>>> card.  Can anyone point me in the right direction?
>> Hm. Completely the same problem.
>>
>> Can someone help?
>>
>> Here is the loghttp://pastebin.freeswitch.org/20447
>>
>>
>>
>>
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>
> -- 
> Tim Bock
> Synacktics, LLC
> www.synacktics.com
> (505)795-1511
>
>
> _________________________________________________________________________
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> http://www.freeswitchsolutions.com
>
> 
> 
>
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