Can any one help me in understanding the concept of PTI. As it is initially assigned by UE in PDN request message. Should it be same in Activate Default EPS Bearer Context message? If we need to established a dedicated bearer(N/w initiated) then also it remain same or can be chnaged by UE. If we use the PTI value in Dedicated bearer context request message same as that we already using in default radio bearer , we are geeting a reject message with cause PTI Mismatch and PTI value in the reject message as 0. So can i interpret that PTI value in the dedicated bearer context request should be zero.
please make me clear.
I am also having some confusions on how to play with PTI. But I think I can answer your query partially...
1)PTI is an identifier for a particular transaction(a series of related message flows)
for ex if you sent a PDN Connectivity Request, subsequent Default EPS bearer Context Activation Request and response for that should use the same PTI.
2)For a different set of ESM messages(like Dedicated EPS bearer Context Activation Request and its corresonding responses) should use a different PTI.
You should be careful when handling PTI. You should release a PTI on sucessful completion of a transaction(request/response which leads to sucess of failure of the procedure).
You should store the valid PTI's once the procedures involved in it is completed(could be sucess or failure).