Hi All,
I have certain queries about the session timer behaviour in the SIP Stack.
The scenario is as follows :
SIP Stack
N/w
At T0s
INVITE
-------------------------------------------------------------------------------->
(having SE=600 &Min-SE = 600 )
100 Trying
<---------------------------------------------------------------------------
180 Ringing
<-------------------------------------------------------------------------
200 OK
<-------------------------------------------------------------------------------
(having Require:timer,SE=600,refresher=uas)
ACK
---------------------------------------------------------------------------------->
<---------------------------------Call Connected
--------------------------------->
At this point the Call is connected and the session timer is started by SIP
Stack when 200 OK from the Network is received by the SIP Stack.
After this, SIP Stack sends out a Re-INVITE with as the new offer(as the
version number in the o-line is incremented here).
At T0+8s
INVITE
--------------------------------------------------------------------------->
(Version number in o-line of Re-INVITE SDP is incremented by 1)
200 OK
<-------------------------------------------------------------------------------
(having SE=19200,refresher=uas)
ACK
---------------------------------------------------------------------------------->
At T0 + 485s
BYE
---------------------------------------------------------------------------------->
The call is terminated with BYE by the SIP Stack after 485 seconds.
Here I have few doubts:
1) The refresher is network here in both the cases.
The second 200 OK response is sent for the "Re-INVITE with new offer"
containing the greater values of session timer than the first 200 OK.
So, does the new value of Session-Expires=19200s in second 200Ok should be
considered as session refresh request by the SIP Stack ?
2) Should the SIP Stack restart its session timer with the new value "19200" or
if the SIP Stack should restart its timer with the old value "600" on receiving
second 200 OK ?
3) Here, the call is terminated with BYE after 485 seconds by the SIP Stack.
What should be the exact time to terminate the call considering the fact
that SIP Stack is running the session timer with the values received in 200 OK
responses?
Please share the references from the RFC to support the above queries.
Regards
Priya Arya
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