Routing of Diameter messages in a DSR with PCA activated is divided into ingress routing and egress routing. Ingress routing includes routing of Diameter requests and Diameter answers to the PCA application from a remote peer. Egress routing includes routing of Diameter requests and Diameter answers from PCA towards a remote peer. A remote peer can be a policy and charging client, a PCRF, an OCS or another DSR. Diameter requests can be initiated by both clients and PCRFs/OCSs.