On 08/02/07 20:04, Daniel Corbe wrote: > Out of curiosity are you affiliated with the OpenSER project? yes, I am, very deep involved actually, from its beginning. > If so does OpenSER support SCTP? It does, since few days ago. It came as a contribution from Connecticut College, I reviewed and integrated in OpenSER and did the initial testings. > Is that why you need a phone that runs over SCTP? Yes. In fact, other SIP entity with SCTP support is fine (of course, at a low cost). I would like to test with other implementation, you know, interoperability in VoIP/SIP was all the time a pain in the ... > > What's the purpose if you have other more reliable transport > mechanisms for SIP such as TCP? TCP brings a lot of overhead, it is one-to-one communication model, while with SCTP you get one to many, as with UDP. For SIP servers able to support large number of online subscribers, TCP reduce the capacity a lot. Also, for NAT, TCP is problematic if the phone does not maintain the connection open, it is basically impossible to open the connection from server side.
The problem I see with UDP is fragmentation and encryption. SCTP and TLS-SCTP overcome them. We face now big SIP messages, especially in IM&Presence extensions. > > AFAIK the only thing in heavy deployment in telephony that uses SCTP > is SIGTRAN and family. OK, so, then here is another question, do you think that SCTP won't make it to the end devices (e.g., phones)? Cheers, Daniel > > -DAniel > > On Aug 2, 2007, at 12:30 PM, Daniel-Constantin Mierla wrote: > >> Hello, >> >> I couldn't find much about SIP phones with SCTP support. Are you aware >> of any? >> >> OpenSER introduced support for SCTP and for testing it was used: >> >> [udp] -------- [udp] openser [sctp] ------------ [sctp] openser [udp] >> ------------ [udp] >> >> But using against other devices is really the challenge. I found some >> references to a modified KPhone version, but no luck to get it. >> >> Thanks, >> Daniel >> >> -- >> http://www.openser.org >> >> _______________________________________________ >> Sip-implementors mailing list >> Sip-implementors@lists.cs.columbia.edu >> https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors > > > ____________________________________________________________ > This e-mail (including attached documents) may contain confidential or > proprietary > information intended only for use by the named recipient(s). Use by > persons > other than the named recipient(s), further dissemination, or copying > of this > email is prohibited unless authorized by the sender. > _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
