Finaly found the solution. Was already discussed in 2013. See:
https://lists.kamailio.org/pipermail/sr-users/2013-September/079765.html

Thanks for the input.
Kristijan


2017-10-02 12:33 GMT+02:00 Kristijan Vrban <vrban.lkml@gmail.com>:
Hello,

i need a "success_route" which does the same as "failure_route", but only for
positiv 2xx reply. Is something like this available?

Background: i forward REGISTER to external registrar server, and only what to save the location on positiv reply to REGISTER. Without doing the authentication myself.

I tried to save the location in onreply_route, but then the contact of the external registrar server is
saved. So i need a status check in the REQUEST_ROUTE.

Best
Kristijan