This example of a multi-cluster network service comprises a VNF (Virtualized Network Function), a CNF (Containerized, or Cloud-native Network Function), and a PNF (Physical Network Function).
It provides an end-to-end telephony service based on Asterisk PBX between a central site and an edge site. An SIP/RTP trunk is set up on a data plane, which is implemented as simple routing for demonstration purposes, but could be extended to a full-blown SD-WAN. The result is that SIP phones connected to either site can all call each other.
A TOSCA-ochestrated version of this is included as an example for Turandot.