On 05/07/2012 06:56 AM, Mohit Soni wrote: > Hi all, > > I want to explore the case where a FAX call is made using the SRTP. > > The case is like this, > > UA-1 UA-2 > ------------------INVITE (SDP = SRTP)-----------------------> The > UA-1 generates INVITE with desired SRTP credentials > > <----------------200 OK (SDP = SRTP)------------------------- The > UA-2 responds with 200 OK with negotiated SRTP credentials > > --------------------------------ACK------------------------------------> > > ---------------------SRTP with FAX tones----------------------> FAX > tones in secure RTP packets are exchanged between UA-1 and UA-2 > <-------------------SRTP with FAX tones------------------------ > > <-------------------INVITE (T.38 UDPTL)------------------------- > UA-2 identifies the FAX tone and determines that the call is FAX call and > sends re-INVTIE with T.38 UDPTL as it is configured as FAX option in it > > ---------------------200 OK (T.38 UDPTL)----------------------> > UA-1 responds with 200 OK to complete the FAX transmission over UDPTL > > <-------------------------------ACK------------------------------------ > > <-------------non secure T.38 UDPTL packets-------------- UA-1 and > UA-2 stops secure RTP and exchanges the FAX over non secure UDPTL packets. > ---------------non secure T.38 UDPTL packets-----------> > > > Is this a valid scenario?
What is your definition of 'valid'? It is certainly compliant with all the relevant RFCs and ITU-T recommendations, if that's what you mean. > Is there any device/UA who behaves like this? Yes, I suspect there are many devices that operate like this, if they support both SRTP and T.38. This would be a very common occurrence if the user of the device has enabled SRTP. > Is it practical to update the session of secure RTP with non secure UDPTL > (or even normal RTP) using re-INVITE at the middle of the session? Can you explain what you mean by 'practical'? -- 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
