[Freeswitch-users] SIM7100 LTE modem with USB audio

[Stanislav Sinyagin]

On Thu, Aug 3, 2017 at 3:51 PM, Tihomir Culjaga <tculjaga at gmail.com> wrote:
> how are you going to instruct mod_ttyusb_audio top open audio channel on a
> specific tty ? are you planing to provide the api in ESL ?

a command like "ttyusb connect /dev/ttyUSB3 <uuid>"

before that, a command "ttyusb device /dev/ttyUSB3 8000 L16" would
tell the module what codec to use.

After the call is finished, issue "ttyusb disconnect /dev/ttyUSB3", or
it would disconnect automatically when the channel is destroyed.


>> Once it's done, the signaling could be done either within FreeSWITCH,
>> or in an outside ESL daemon. An external daemon would allow more
>> flexibility, but there's a burden of running one more process.
>
>
> although it can be much more flexible and faster using an external ESL
> daemon, i'd prefer to make it in FreeSWITCH as a module ... e.g. mod_hayes

the commands are very different for different vendors (I compared
Huawei against Simcom, and it's a lot of difference), so there should
be some vendor-specific extensions. Either a rich XML file defining
the whole dialogue, or a per-vendor module in FreeSWITCH. Difficult to
say, I'm not that far yet.

>> In regards to udev rules -- you actually don't need them. The logic of
>> finding the modem and matching it against IMEI and IMSI is already in
>> mod_gsmopen (was that Giovanni who implemented it?). It just needs a
>> bit of improvement in making it more vendor-independent. Also I would
>> do matching on IMEI OR IMSI, not the AND condition that is in the
>> module currently.
>>
> are we sure IMEI and/or IMSI will always present ?

yes, as per GSM standard. But again, commands retrieving them are
different between vendors. And anyway, that would only be one method
of selecting a device. There should always be a way to point to a
specific ttyUSB device explicitly.

>> I actually do have a set of udev rules, they are in fact needed for
>> data connection:
>> https://github.com/ssinyagin/wwan_udev_rules
>> But they fail if you have more than one modem, and here's an explanation:
>>
>> https://txlab.wordpress.com/2017/05/19/two-lte-modems-with-pc-engines-apu3/
>
>
> this is specific HW :=) .. im positive there is a work around this problem

no, this is a generic problem, and a solution for a specific host hardware.