[Freeswitch-users] FreeSwitch and GSM/HSPA Modems

[Giovanni Maruzzelli]

On Thu, Jan 7, 2010 at 7:27 PM, Michelle Konzack
<linux4michelle at tamay-dogan.net> wrote:
>> it supports all modules that accepts standard ETSI AT-GSM commands
>> (so, let's say all of them).
>
> Currently I havepayed over 20.000 Euro for ETSI and ANS specs  and  have
> currently not the money to buy more...  Are the ETSI  AT-GSM  specs  are
> free available?  --  If yes, I need them!

yes is part of the GSM specifications that are freely available. Just
google for them. Anyway, any GSM modem or module (but not all
cellphones) supports at least a fair share of those specs.

>
>> Maybe I do not understand the second question, what do you means for
>> Endpoints?
>>
>> If you're talking usb endpoints, you'll need a modem endpoint (that
>> can be seen as a serial port), and (if you need audio, eg not just
>> SMSs but voice calls too) you need an audio endpoint (that can be seen
>> as a soundcard).
>
> I mean the USB-Endpoints...
>
> If you have an USB-Microcontroller where the USB port is  a  device,  it
> identify it self over the Endpoint 0 and is for us non usable.
>
> And no it comes, where I haveproblems to understnd HOW the GSM Modem  is
> working but I will assume some things:
>
> The EP1 of the USB-pot is configured for bidirectional Data transmission
> andwill controll out Device and is normaly  configured  as  /dev/ttyUSB0
> and this is, where we use the AT commands to  get  infos  from  the  GSM
> modem/cellphone and send/receive SMS.
>
> Now We need EP2 and configure it as streaming output for the Audio port.
>
> EP3 would be the streaming input for the Audio Port.
>
> is this right up to here?
>
> Then, EP4 would be the bidirectinal dataport  for  the  UMTS  and  HS*PA
> Tranceiver, since it is entirely independant from the rest  of  the  GSM
> modem/cellphone.
>
> Is this right?

Is completely up to the implementation.

I suggest you use lsusb with full debug/verbosity turned on, it will
tell you (almost) all.


>
> If yes, then it is easier as I was thinking...
>
>
>> Many modules and cellphones can be seen as HDSPA or GPRS modems, just
>> check their specs.
>
> My "Nokia 6120 classic" has in total 13 endpoints...  Hell, where can  I
> get an USB-Microcontroller which support this mass of USB Endpoints?
>
> Most ARM9/11 support not more then 7 or 9.  :-(

I think you just needs to interface the modem endpoint and the audio
endpoint. The others are probably Human Interfaces for volume, color,
keyboard, whatever. You control the full phone features through AT
commands exchanged through the modem endpoint.


>
>> For audio, if the module/cellphone/modem does not offer an audio usb
>> endpoint (eg cannot be seen as a soundcard) one trick is to connect
>> the headset jack to an usb soundcard (you can find soundcard with for
>> factor like a dongle based on cm-108 chipset for under $10). I'll
>> publish the schema of the cable needed from hadset jack in the
>> phone/module to the usb soundcard).
>>
>> If I have not get what you asked, please explain more your question.
>
> Most important things are the above desibed understanding  problem  with
> the USB Endpoints
>
> I have the HSPA and GS frontends (Maxim and Infineon chips) here and  my
> selfemade simple GSM/GPRS cell-phone is already working,  but  has  less
> functionality as the cell-phones from Year 2000  :-D

you don't need them all (at least if you don't want to make dirty pics
with a kludge full of wires... hey, that can be arousing! :))

I suggest you use a ready-made GSM/GPRS/HDSPA/whatever module, that
contains all that you need and is available from Chinese suppliers for
very low prices. You can find some module that allows you to directly
tap in the GSM pcm audio stream, that would means you will not need to
sample and convert from analog to digital (so, no cpu power at all, no
dsp, no nothing).


If you would like to keep me in the loop, I would like to know how you progress.

Happy hacking

-giovanni

>
> Hey, ist is my first experience of developing GSM stuff.
>
> I an to develop a VERY simple GSM/UMTS/HSPA USB-Modem which do  its  job
> without balast.
>
> So if someone can help me with infos, I am very open...
>
> I prefer FreeSwitch over Asterisk which froze in the  last  2  years  to
> many times in situations where it should not freeze, exspecialy if  I  a
> call a Chip-Manfacturer (Maxim/TI) Tech-Support.  --  It is not funny!
>
> Thanks, Greetings and nice Day/Evening
>    Michelle Konzack
>    Systemadministrator
>    Electronic Engineer
>    Tamay Dogan Network
>    Debian GNU/Linux Consultant
>
> --
> Linux-User #280138 with the Linux Counter, http://counter.li.org/
> ##################### Debian GNU/Linux Consultant #####################
> <http://www.tamay-dogan.net/>                 Michelle Konzack
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-- 
Sincerely,

Giovanni Maruzzelli
Cell : +39-347-2665618