I've configured the following architecture :

SipML5 -> OverSIP -> Kamailio -> OverSIP -> SipML5

In cas we have two clients that are registered but not authenticated with Digest Authentication. One client can call the other thanks to Kamailio (SIP INVITE correctly routed) : I would like to know how the clients locations are handled, I have checked the Kamailio database and found nothing there.

Although Kamailio doesn't know in advance the private identity of each client, the SIP INVITE using the public identity works fine after confirming SIP REGISTER with nothing stored in the database.

Please help me understand how Kamailio works.
Thanks in advance.