[Freeswitch-users] Running FreeSWITCH on softmodem

[Steve Underwood]

On 01/25/2012 04:07 AM, Sebastian Tarach wrote:
> ~I'm hoping I'm not doing something wrong by replying to this message.
> Sorry I'm using message boards and irc most of the time and not
> mailing lists.
>
> Well after installing sl-modem-daemon and modem-cmd I was able to call
> my mobile phone bo using command
> modem-cmd /dev/modem ATD9<mobile phone>  - 9 tells my Panasonic
> KX-T61610B to use first outside line available.
>
> After a while I heard my mobile phone ringing. That's why I'm not
> really convinced that it won't work because it will lack the drivers.
> Well maybe FreeSWITCH needs some special drivers I don't know of.
Did you get good voice results during your test call? No? Maybe there 
are good reasons.

The sl-modem-daemon runs the modem interface at 9600 samples/second. 
Most modem interfaces, when used for modem work, run at that sampling 
rate. It happens to simplify the modem's DSP a bit. So, you have a 
driver which can control your modem port, but you have two problems. One 
is the sampling rate is not the 8000 samples/second rate all the 
telephony systems works at. The second is the driver APIs are 
proprietary, and not like the APIs used to control mainstream telephony 
cards, like those made by Sangoma and Digium.

The source code for the driver module of sl-modem is available. For some 
hardware you can find the information that will allow you to set the 
hardware to sample at 8000 samples/second. All the elements are 
available for building a driver that would be compatible with FreeSwitch 
(or Yate, or CallWeaver, or Asterisk, etc.). None exists today. If you 
have the time, skills and enthusiasm quite a few people might love to 
see such a  driver. It used to be quite an interesting thing to have, as 
a lot of notebooks had similar modem ports. Now they are disappearing, 
its becoming less interesting every time the makers refresh their models.

Steve