[asterisk-users] Using a mobile phone via USB as an extension

[Nick Hill]

Hello Sasa

The page you point to doesn't talk about USB connectivity for chan_mobile. It 
does talk about bluetooth connectivity, which can be achieved by way of a USB 
bluetooth dongle, but that is not the same thing.

I am talking about using standard interfaces exposed by mobile devices (mobile 
phones or USB dongles), exposed via USB, to establish voice calls as an 
extension to asterisk. And examining whether the standard CDC modem interface or 
any other standard interface generally carries the required commands.

There are several potential benefits to using the USB approach:
1) Devices will be immune to interference from other 2.4Ghz devices. Bluetooth 
is prone.
2) Potentially better call quality. Using bluetooth, the call will need to be 
converted from the VOIP codec, to PCM then to the bluetooth codec then to the 
over-the-air mobile codec (GSM), with associated latency. There may be a 
possibility of cutting one of these conversions.
3) This could be used with a USB data dongle interface, which are cheap, 
relatively simple, and are powered from the USB port. They also generally offer 
great sensitivity over the air.
4) The bluetooth approach is dependent on a working (bug-free) bluetooth stack, 
with specific hardware, which may or may not be available.
5) less software and hardware needed in the chain, so potentially more 
maintainable and reliable.


The bluetooth approach has some advantages:
1) The bluetooth interface is standardised and any device should theoretically 
work with any other of the given generation. The required codecs, for example, 
are well defined. (in practice, this isn't the case - for example, the Nokia E65 
is bluetooth capable and doesn't work, and the chan_mobile is fussy about which 
bluetooth dongles you use).
2) Even if the USB interface does provide necessary interfaces for voice 
telephony, they may not be well tested. (buggy). We don't know - but then, the 
bluetooth approach is, in practice, hardware dependent also.
3) Bluetooth dongles are "swallowed" by a mobile phone. One dongle needed for 
each phone/channel. (they are cheap, but may have other ramifications).

Someone may have investigated the USB approach already and discounted it. Or if 
not, it may be worth further examination.

Carlos indicates that USB support may be available in chan_mobile but I can't 
find any references to it, and I think Oliver is looking for more info as well.





Sasa Bobek wrote:
> Just google/bing it. http://voip-info.org/wiki/view/chan_mobile
> 
> On Thu, Jul 9, 2009 at 12:56 PM, Olivier <oza-4h07 at myamail.com 
> <mailto:oza-4h07 at myamail.com>> wrote:
> 
> 
>     2009/7/2 Carlos Ruiz Diaz <carlos.ruizdiaz at gmail.com
>     <mailto:carlos.ruizdiaz at gmail.com>>
> 
>         Check chan_mobile. Now is mature enough to be used in a server
>         with low CPS.
>         The USB connectivity will be introduced in the close future (I
>         think) but by now it can be connected via bluetooth device.
> 
>     Where did you get this info (USB connectivity for chan_mobile) ?
>     Is there a way to learn a bit more ?
> 
>     _______________________________________________
>     -- Bandwidth and Colocation Provided by http://www.api-digital.com --
> 
>     asterisk-users mailing list
>     To UNSUBSCRIBE or update options visit:
>       http://lists.digium.com/mailman/listinfo/asterisk-users
> 
> 
> 
> ------------------------------------------------------------------------
> 
> _______________________________________________
> -- Bandwidth and Colocation Provided by http://www.api-digital.com --
> 
> asterisk-users mailing list
> To UNSUBSCRIBE or update options visit:
>    http://lists.digium.com/mailman/listinfo/asterisk-users