[SR-Users] Interconnecting two Kamailio IMS Networks

Hi, I have P-CSCF, I-CSCF, and S-CSCF instances of Kamailio running with rtpengine. I can have a VoLTE call over a 4G network (using Open5GS) using Kamailio with two phones on the same IMS network, no problem. I have leveraged the docker_open5gs project to do this. For Kamailio, I have some IMS-related questions for when the Called-Party is not within the IMS network as I'm interested in what may be required to interconnect two Kamailio IMS networks. - Does Kamailio (or anyone you may know) have example configuration files for instances of a BGCF, IBCF, or TrGW? - If the S-CSCF determines that the Called-Party is not within the IMS network, is there an example configuration file of where the S-CSCF can forward the SIP INVITE to a BGCF / contact the IBCF directly? - If "no" to the above, are the BGCF, IBCF, and TrGW instances necessary to facilitate a call between two networks? Can Kamailio emulate multiple networks and instead have the S-CSCF of the originating network simply send the SIP request to the I-CSCF of the destination network (selected via DNS lookup) and use the single rtpengine instance between the two networks rather than using a BGCF, IBCF, and TrGW? Thank you very much for your help, Derek