[Asterisk-Users] T.38 fax with SIP devices

[Moody]

Hello Mark, 

I have been working on a similar plan but am still looking for
reasonable/tested hardware - can you tell me what devices you are
using?

Thanks, 

Jonathon


On Apr 7, 2005 7:01 AM, Mark Dutton <replies at datamerge.com.au> wrote:
>  
> Hi there 
>   
> I have a SIP ATA with a fax machine attached and a SIP FXO gateway to the
> PSTN. When I try to send faxes in either direction, I get nothing but stony
> silence. I have changed the gateway and the ATA to peer to peer mode to test
> them and they happily do the T.38 thing and faxes flow. 
>   
> It seems that they initially negotiate a G.729 codec, which is what I want
> and then when the receiving end detects the fax machine, it wants to
> re-negotiate and use the t38fax codec. This is the working the Micronet
> devices use at least. 
>   
> When I put the units into proxy mode and run them through Asterisk, they
> fail at the negotiation stage. 
>   
> Now I have learned from my dealings with Asterisk and the newsgroup that
> Asterisk does not do T.38. However, why should it not let devices do T.38?
> My debug messages from Asterisk don't show it saying no, but the gateways
> don't wont' setup the T.38 on Asterisk. 
>   
> I have chanded sip.conf to allow=all and there are no explicit rules in the
> registrations for the gateways. 
>   
> Does anyone have an idea here? 
>   
> For this venture to be truly usable, I have to be able to get FAX working at
> this basic level. 
>   
> Regards 
>   
> Mark Dutton 
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