[asterisk-dev] Routing data modem calls

[Matthew Fredrickson]

On Jul 28, 2006, at 7:05 AM, Brian Candler wrote:

> On Fri, Jul 28, 2006 at 10:27:58AM +0100, Brian Candler wrote:
>> Does anyone know if there's a standard mechanism for carrying data 
>> modem
>> calls over a VoIP-type network? I know there's T.38 for fax, but I 
>> have not
>> been able to find something equivalent for generic data modem calls.
>
> To answer my own question, at least in part - there *is* a standard for
> this, called V.150 (= V.150.0 + V.150.1), and Googling for that turns 
> up the
> sort of thing I was looking for.
>
> (Sometimes, a bookshop is better than the Internet. I found a 
> reference to
> this standard in an O'Reilly book called "Switching to VoIP". However, 
> even
> this book says that if you need legacy modem services, you should just 
> keep
> some POTS lines around to support them :-)
>
> I notice that the source for Asterisk 1.2.10 doesn't refer to V.150, 
> but
> Asterisk SVN at least decodes the frame type in frame.h / frame.c. 
> Does this
> mean there is some plan for this in the pipeline?
>

In the course of getting T.38 support and infrastructure into Asterisk, 
the thought that it might be used for V.150 modem frames was there as 
well.  However, I do not think that anyone has (as of yet) started 
working on it.  The man to talk with is Steve Underwood though, he 
probably has the most understanding of this specific application and 
was the one responsible for T.38 passthrough support in Asterisk.

Matthew Fredrickson