changing Display Name during a call

[sergeysi]

I try to implement the following scenario:
User dials a number and phone sends it to IP-PBX. PBX sends an answer of 180 or 200 and dials the number. In parallel PBX tries to find the number in different catalogs and if it finds the number it should send a command to the phone asking it to change Display Name (e.g. name of the dialed person) so the user can see name of the person he is trying to call.

Is it possible to use UPDATE method to change display name during a call? Is there any example of SIP packet? Or maybe there are other methods?
I actually tried to use UPDATE method but phone (T22P v7.72.14.3) always answers "481 Call Leg/Transaction does not exist" though the packet contained the same Call-Id and From and To tags as in initial INVITE and 200 OK answer. Working example would be very helpful.