Hey kamailio team, 

When are the callbacks in the dialog module for updating $dlg_var(cseq_diff) called?

I am trying to dynamically enable / disable cseq updates (some specific carriers need it and some don't) by setting $dlg_var(cseq_diff)=$null prior to sending the request but it seems like the callback happens after relaying.

For example I tried various locations:

- prior to t_relay()

- in onreply_route[]

- in failure_route[]

- in event_route[tm:local-request]

- in event_route[tm:local-response]

I also tried setting modparam("dialog", "initial_cbs_inscript", 1) and calling dlg_manage() prior to routing and those didn't seem to be the right callbacks either.

Either the callback that updates $dlg_var(cseq_diff) occurs after t_relay() / forward() is called or setting $dlg_var(cseq_diff)=$null has no effect.

Is dynamically turning CSEQ updates on / off possible by overwriting $dlg_var(cseq_diff)?

Or would this require new logic in the dialog module to be supported?