12-18-2015 11:23 PM - edited 03-17-2019 05:18 AM
12-18-2015 11:47 PM
It is provisional acknowledgement. As name says, it is used to acknowledge SIP provisional responses like 180 Ringing, 183 Session Progress etc.
When you use SIP on UDP, by default provisional responses are sent unreliability (does not re-transmit). Lets assume if 180 Ringing is lost over the network, caller will not get RBT and suddenly will listen the word 'Hello'. To avoid this, '100rel' extension is used during call setup which indicates called party to send provisional response reliably and keep re-transmitting until PRACK message is received or timeout happens.
Refer RFC 3262 for more details.
- Vivek
12-19-2015 03:59 PM
Hi Manzoor,
Here is a excellent document for your understand about PRACK:
http://www.cisco.com/c/en/us/support/docs/voice/session-initiation-protocol-sip/116086-configure-cube-cucm-sip-00.html
Hope this helps.
Rate the post accordingly.
-Regards,
Kevin Monteiro
12-18-2015 11:47 PM
It is provisional acknowledgement. As name says, it is used to acknowledge SIP provisional responses like 180 Ringing, 183 Session Progress etc.
When you use SIP on UDP, by default provisional responses are sent unreliability (does not re-transmit). Lets assume if 180 Ringing is lost over the network, caller will not get RBT and suddenly will listen the word 'Hello'. To avoid this, '100rel' extension is used during call setup which indicates called party to send provisional response reliably and keep re-transmitting until PRACK message is received or timeout happens.
Refer RFC 3262 for more details.
- Vivek
12-19-2015 02:03 AM
Thanks for your response.
ms-client-diagnostics: 51004; reason="Action initiated by user"
above is a trace part from the calling party in the "cancel" message. The outbound call was rejected by the server end; then why this is initiated by Calling party.
12-19-2015 02:25 AM
In addition to what Vivek has said, PRACK is also used for early media. In SIP media flows at when we get or send 200 OK, however there are scenarios where we need media to flow before that.
A typical example is when the called party wants to play announcement. In scenarios like this we will use prack to send media either in 180 or 183 progress messages.
12-19-2015 07:10 PM
Hi,
Where are UDP and TCP ports used in SIP environment
Among INVITE, BYE, ACK, CANCEL, INFO, UPDATE, REFER, NOTIFY, BENOTIFY, OPTIONS.
12-20-2015 05:52 AM
Every protocol needs a transport mechanism. SIP uses UDP, TCP, and SCTP for transport.
In each of your sip Methods, (everything in CAPS) you can see what transport protocol by looking at the via header.
Examples:
This INVITE uses TCP as the transport protocol
INVITE sip:1598@10.100.24.171:5060 SIP/2.0
Via: SIP/2.0/TCP 10.100.42.141:5060;branch=z9hG4bK66a0972f72e00
In this example, the INVITE uses UDP
INVITE sip:208774@10.100.40.100:5060 SIP/2.0
Via: SIP/2.0/UDP 10.100.140.14:5060;branch=z9hG4bK39e90e56b5e1ea
This OPTIONS ping uses UDP
Sent:
OPTIONS sip:02079501251@10.106.33.24:5070;transport=udp SIP/2.0
Via: SIP/2.0/UDP 10.105.40.200:5060;branch=z9hG4bK10D683B1078
This BYE uses UDP
BYE sip:0189@10.100.140.20:5060 SIP/2.0
Via: SIP/2.0/UDP 10.100.10.14:5060;branch=z9hG4bK39e90b13e4c448
12-20-2015 11:16 PM
Sir,'
Thanks for your mail.
At the invite message, I can seen in both TCP and UDP 5060 port is used. COuld you please explain that sir!
12-21-2015 12:35 AM
You can't have both tcp and udp in the same Invite. Please share the INVITE trace
12-21-2015 04:12 AM
Hi,
Not in the same INVITE. From the above i am asking ,is 5060 TCP or UDP port?
12-21-2015 07:54 AM
5060 is for SIP. That is the port that SIP protocol uses. This can run on either UDP or TCP.
12-19-2015 03:59 PM
Hi Manzoor,
Here is a excellent document for your understand about PRACK:
http://www.cisco.com/c/en/us/support/docs/voice/session-initiation-protocol-sip/116086-configure-cube-cucm-sip-00.html
Hope this helps.
Rate the post accordingly.
-Regards,
Kevin Monteiro
12-19-2015 04:17 PM
Kevin, (+5)
Great document thanks for sharing it.
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