[SIPForum-discussion] Query for Time T4

Nitin Kapoor nitinkapoorr at gmail.com
Fri Jan 8 22:20:15 UTC 2010


Timer T4 basically represents the amount of time the network will take to
clear messages between client and server transactions. The default value for
T4 is "5"seconds. Also T4 is a constant and not set based on T1.

You can refer to RFC 3261 Sec for more detail.

Apart from that I am not sure after expiring the T4 timer, how your A party
will send you another ACK. Also 408 is for Request Time Out not for *Call
leg doesn't exist.

May be someone else can give the answer of your second query in more depth.


Nitin Kapoor

2010/1/8 lakhan patel <lakhan.p at gmail.com>

> Hi All,
> I have doubt about T4 Timer and what happen if any dialog is in terminated
> state and other side tries to communicate with previous dialog which was
> terminated?
> After INVTE from A to B, B sends *404 Not found* and B received *ACk *for
> *404* but when A-side receive *404 *and send *ACK *for *404 *Call goes in
> *Confirm* state and after *5second(T4 timer fires) *it goes under *Terminated
> *state and after that if we are sending Re-send *ACK *for *404 *it should
> reply with *408 Call leg does not exist*.
> *Can Any body tell me is it correct call flow or not?*
> --
> Thanks & Regards
> Shivlakhan Patel
> Email: lakhan.p at gmail.com, lakhan.p at hotmail.com
> IBM India Private Ltd. Bangalore
> Contact: +91-9902791177
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