Hi Tamjid,
As per RFC-3261, Contact is optional in 1xx but it is mandatory in 2xx.
Refer table in section 20.1.
Header field where proxy ACK BYE CAN INV OPT REG
___________________________________________________________
Contact R o - -
m o o
Contact 1xx - - -
o - -
Contact 2xx - - -
m o o
Contact 3xx d - o -
o o o
Contact 485 - o -
o o o
Contact is mandatory in INVITE request and 2xx response of INVITE. 1xx is also
used for making early dialog however 2xx response only comes from the final
destination.
Regards,
Alok Tiwari
Aricent
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Tamjid Ali
Sent: Saturday, November 03, 2012 10:09 AM
To: [email protected]
Subject: [Sip-implementors] Is contact header mandatory for each sip messages?
Hi,Can anyone clear me why contact header present in each sip message even
after knowing each other after 1xx response? If contact header is not present
in subsequent sip messages then what will happen??
Thanks®ards,Ali
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