[Freeswitch-dev] openzap information

devel at thom.fr.eu.org devel at thom.fr.eu.org
Tue Jan 19 11:15:04 PST 2010

Could you please give me some information as starting point on this.

I don’t know for BELL standard, but in V23, there different ways of sending
the CLIP : before the ringing signal and during the first silence between 2
consecutive ring signals.

By looking at the sequence, it seems to me as if the first one (CLIP before
the ringing signal) is used. Again, I don’t know in the BELL standard (but I
guess it should be somehow similar), the need to be some signal (called TAS)
sent to the TE to let him know the CLIP is coming (so that it can set the
line impedance in order to receive it).


So could you confirm that CLIP before the ringing signal is coded in
openzap, and indicate which type of TAS is used and where is this part coded
in openzap.


Thanks in advance




De : freeswitch-dev-bounces at lists.freeswitch.org
[mailto:freeswitch-dev-bounces at lists.freeswitch.org] De la part de Michael
Envoyé : lundi 18 janvier 2010 23:18
À : freeswitch-dev at lists.freeswitch.org
Objet : Re: [Freeswitch-dev] openzap information + mod_say_fr contribution


In regards to the CLIP.  The bulk of this code for V23 as you can see is
already there, we just need this troubleshooting as we have never tested it.
If you can get a raw recording of the channel it will probably help in
testing.  As for the mod_say_fr, please file this on




On Jan 18, 2010, at 5:01 PM, <devel at thom.fr.eu.org> <devel at thom.fr.eu.org>



First let me congratulate for this great software.


I was trying to diagnose a problem with my analog sangoma card, and FXS port
giving intermitent ringing and not sending CLIP.


I could see the intermitent ringing comes from this line.

zchan->ring_time = zap_current_time_in_ms() + wp_globals.ring_on_ms;


Setting zchan->ring_time could solve my problem, so could anybody indicate
how to configure ring_on_ms (preferably in an XML configuration)



The second point about CLIP is more difficult. First, let me indicate that
I’m residing in France and therefore using carrier and phones complying to
european standard.

About CLIP, I could see the V23 standard modulating frequencies are being
populated (in fsk_modem_definitions in fsk.c). However, in
zap_channel_send_fsk_data in zap_io.c, I could see that the BELL standard is
hardcoded. Replacing the modem type with FSK_V23_FORWARD_MODE2 (which by
what I could read seem to apply to me), I could see no difference.


As I could not find as much relevant information as I would like in V23
(apart from the frequencies for the FSK), I was wondering what were I could
find some information that could help to fix this.


I don’t know exactly what carrier_bits_start, carrier_bits_stop and
chan_sieze_bits refer to, but I could find in that document
(http://www.cs-strumentazione.com/manuali_pdf/clip.pdf) that « The Channel
Seizure is present only in FSK-V23 Protocol. It

consists in a series of 90 to 300 alternate SPACE/MARK bits


Considering this, I guess that I should use the else branch in the test «
zchan->token_count > 1 ». What does this token_count refer to and where
should I set it.


I’m still trying to figure this out (and will of course contribute the
result of all this), so any help appreciated.


I also did a contribution to mod_say_fr (to take into account the specific
french idioms in saying date and time). Could you please tell me how to
contribute this ?


Thanks in advance




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