[SR-Users] TimeStamp header

[mustafa rifaee]

Hello all;
I need some Clarification about timestamp header in RFC 3261; i need to use
it to estimate the RTT value;
how it is work in this scenario?:

           Invite
  UA -------------------->   Proxy1
   |                                |          Invite
   |                                | ------------------------------
--------->Proxy2
   |                 100 trying
|                                             |
   |   <---------------------------|
                                       |          invite
   |
|                                             |
   |                                |
                                          |
--------------------------------------->UA2
   |                                | <-------100 trying-------------------
|                                            |
   |
|                                             | <--------180
Ringing--------------  |
   |                                | <---------------180 Ringing-------
|                                            |
   |
|                                             |
                                          |
   |<---180 Ringing----------|
|                                            |


UA send invite to proxy1 with timestamp=10 ; then the Proxy1 send the invite
message to proxy2 and reply with provisional response (100 trying) and with
timestamp=10 0.5;

When UA receive 100trying; UA will adapt its retransmition timer T1 to the
calculated value from timestamp;
then UA adapt T2 Timer value; is This true?

Here Can Proxy1 send invite message with timestamp header?;
 for example timestamp=8 and when proxy2 recive invite request, it send it
to UA and he send 100 trying to proxy1 with
 timestamp=8  0.4;

Please Help me;
Thanks;
Mustafa AL Rifaee
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