[asterisk-users] how many UDP ports is required for 1 call

[virendra bhati]

Hi All,

I read all URL which was mention on post. Now SIP,UDP and RTP communication
process is clear, the way of communication and port's used in that process.

http://blog.lithiumblue.com/2007/07/understanding-relationship-between-sip.html

This blow is best for understanding the packet reading and port
information. Nice blog.

As per that blog UDP and RTP both are used in SIP communication process and
RTSP is used with RTP for controlling the packets.



On Thu, Feb 23, 2012 at 6:12 AM, Gilles <codecomplete at free.fr> wrote:

> On Wed, 22 Feb 2012 18:04:38 -0600, "Kevin P. Fleming"
> <kpfleming at digium.com> wrote:
> >SIP is most commonly transported over UDP, not TCP.
>
> To complicate things further, there's "symmetric RTP":
>
> "A device supports symmetric RTP if it selects, communicates, and uses
> IP addresses and port numbers such that, when receiving a
> bidirectional RTP media stream on UDP port "A" and IP address "a", it
> also transmits RTP media for that stream from the same source UDP port
> "A" and IP address "a".  That is, it uses the same UDP port to
> transmit and receive one RTP stream.
>
> A device that doesn't support symmetric RTP would transmit RTP from a
> different port, or from a different IP address, than the port and IP
> address used to receive RTP for that bidirectional media steam."
> www.armware.dk/RFC/rfc/rfc4961.html
>
>
> --
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-- 

Thanks and regards

 Virendra Bhati
+91-8885268942
Software Engineer
E-mail-: virbhati at gmail.com
Skype id:- virbhati2
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