[SIPForum-discussion] Use case for changing contact with re-invite

[seshagiri]

Hi

In sip what is the use case for the scenario  to change the contact ip
 with re-invite after the session establishes ?

The scenario is

A calls B through SBC which is B2BUA.
After session establishes A sends re-invite to SBC with new-contact and
receives 200 OK.
This re-invite is not relayed to UA B.

Now B sends BYE , SBC receives and send it to the new contact of A and
receives 200 OK.
This scenario is working fine , but  what is the use case for this ?
i could not able to undrestand it.

A -----INVITE---------->SBC -------INVITE------------>B
A< -----200--------------SBC< ------------200------------B
A -----ACK----------->-SBC ----------ACK------------>B
A -----re-INVITE(New contact)--------->-SBC

A< -------200-----------SBC
A -----ACK------------->SBC
A <-----BYE(to new contact of A)----------SBC< -------BYE------------B


In real-time scenario what is the use of changing the contact with
re-invite ?
i think if UA using DHCP and is going to change IP after
session establishment , in this case it might send re-invite with new
contact , is this correct ?

Pl share your views.


Regards
Sesh
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