On 09/06/2015 03:25 PM, John Andersen wrote:
Well, I know that TCP is offered as an option in many SIP clients, but I don't know exactly what it is used for. It might just be session initiation, and then UDP for voice, and maybe falling back to TCP for file transfers.
SIP, which is the control protocol typically used with RTP can run over UDP or TCP. It is just the control messages and buffer time is not an issue. In fact, SIP is similar to HTTP with plain text and acknowledgements. RTP is the protocol that actually carries the content. It is what's sensitive to delay and jitter.
TCP connections to the sip server can sit idle for looooong periods of time with no traffic at all (essentially until timeout occurs - around 18 minutes). This would drastically reduce the idle traffic needed for presence detection.
It might be that actual sip calls do go to UDB.
I've never heard of SIP calls (actually RTP) on TCP. It uses UDP. Here are a couple of links you may want to read: SIP - https://en.wikipedia.org/wiki/Session_Initiation_Protocol RTP - https://en.wikipedia.org/wiki/Real-time_Transport_Protocol BTW, I have set up VoIP over IPSec VPNs without problem. IPSec tunnels use a connectionless protocol similar to UDP. -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org