Hi Andr?,
On 3/4/08, Andr? Teixeira <coelho at wit-software.com> wrote:
> Hello, i'm new to pjsip and i am with a problem, i've searched for
> examples, tried several things, but I was not able to solve it :(
>
> I'm trying to establish a T.38 fax session, and in order to do that it
> is necessary to follow the following steps. Imagine A wants to send a
> fax to B.
>
>
> 1- A calls B,
> 2- A sends a special tone to B
> 3- B detects the tone
> 4- B sends a reINVITE with it's fax capabilites:
>
> [...]
> m=image <port> udptl t38
> a=T38FaxVersion:0
> a=T38MaxBitRate:14400
> a=T38FaxMaxBuffer:200
> a=T38FaxMaxDatagram:72
> a=T38FaxUdpEC:t38UDPRedundancy
> a=T38FaxRateManagement:transferredTCF
>
>
> 5- A sends 200 OK with the following information in the SDP
> [...]
> m=image <port> udptl t38
>
>
>
> A B
> Invite ->
> <-200 OK
> Special tone ->
> <-INVITE
> 200 ok ->
>
>
> I think i can try two different approaches, but i'm not being able to
> test neither successfully.
>
> 1- change the SDP from the dialog so all my following answers after my
> initial Invite contain a SDP with m=image <port> udptl t38. Trying to
> do that I always get an error of something related to "OFFER"
>
> ...
> pj_strdup(pool_vars, &m_video->desc.media, &pj_str("image"));
> m_video->desc.port = port;
> m_video->desc.port_count = 1;
> pj_strdup (pool_vars, &m_video->desc.transport, &pj_str("udptl"));
>
> m_video->desc.fmt_count = 1;
> m_video->desc.fmt[0] = pj_str("t38");
>
> pjsip_inv_set_sdp_answer(this->g_inv, local_sdp);
> ...
>
What's the exact error code/message that you see?
>
>
> 2- intercept the reInvite and respond with the correct SDP, I am able to
> catch the INVITE from B, by listening all dialog request, BUT I have
> never managed to send an answer :(
>
> Does anyone have any ideia how can I respond to an INVITE received
> inside a dialog and how can I set the SDP to contain m=image <port>
> udptl t38
>
Rather than trapping all dialog events, the proper way to handle this
is to override the on_rx_offer() callback of the invite session. This
callback is called whenever the invite session receives new offer from
remote, either in re-INVITE, UPDATE, or other means.
Please see the comment/doxygen documentation of this callback for more
information.
cheers,
-benny
> Thank you very much
>
> Andr?
