[Freeswitch-users] T1 RBS Support Revisited

[Robert Dyck]

If RBS means robbed bit signalling then it is transmitted in the media bit 
stream but as the name implies it is not used for media. If I remember 
correctly the LSB from every sixth frame is robbed leaving 7 bits and 1 faked 
which would probably be correct about 50% of the time. RBS introduces a small 
amount of distortion. The channel bank will use the state of the signalling 
bit to set the M lead (on or offhook ) of the appropriate channel. The E lead 
sets the signalling bit for the other direction. Think Ear and Mouth.

MF of course is encoded into the bit stream the same as any other audio 
source. To avoid RBS, on/offhook can be transmitted using SF ( 2600 HZ ) in 
band. You would want to disable RBS in that case. Compatible equipment is 
required obviously.

On Thursday 21 August 2008, Brian West wrote:
> Isn't RBS more than just MF?  Unless I'm forgetting something you rob
> a bit.
>
> /b
>
> On Aug 21, 2008, at 7:44 PM, John Wehle wrote:
> >> Is there support in FreeSWITCH for MF?
> >
> > To answer my own question ...
> >
> > Perhaps I can add a ZAP_COMMAND_SEND_MF case to zap_channel_command
> > patterned after ZAP_COMMAND_SEND_DTMF and just use teletone_set_tone
> > to set the proper frequencies???
> >
> > -- John
> > -------------------------------------------------------------------------
> >
> > |   Feith Systems  |   Voice: 1-215-646-8000  |  Email:
> >
> > john at feith.com  |
> >
> > |    John Wehle    |     Fax: 1-215-540-5495
> >
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> Brian West
> sip:brian at freeswitch.org
>
>
>
>
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