On 08/06/2012 05:03 AM, Saurav Sarkar (sausarka) wrote: > What my query is that if there is any implementation that requires T.38 in > the initial call itself? (Say, for example, any Fax endpoint that supports > T.38 in the initial call?)
In the Asterisk community we have come across some occasionally, but we've usually convinced the vendor to change their requirements. However, in these cases they have required *both* T.38 and audio in the initial INVITE. I've never seen an endpoint that supported *only* T.38, and in the latest T.38 recommendation it is suggested that such endpoints should still support INVITEs with audio offers, even if they won't generate any audio. > Call flow, for example: > > SBC > INVITE (T.38 fax) ----->| > |-----> INVITE (T.38 fax) > |<----- 200 OK (T.38 fax) > |-----> ACK > 200 OK (T.38 fax) <-----| > ACK ----->| > <----- Fax Stream -----> > > I am asking this to know if a support of this sort is required on the Session > Border Controller (SBC). And if yes, then what is the mechanism that is used > (because there cannot be any fax tone to start off with). It would seem wise for an SBC to not break a session that is setup initially with T.38. -- Kevin P. Fleming Digium, Inc. | Director of Software Technologies Jabber: [email protected] | SIP: [email protected] | Skype: kpfleming 445 Jan Davis Drive NW - Huntsville, AL 35806 - USA Check us out at www.digium.com & www.asterisk.org _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
