How to route incoming sip calls based on the transport protocol from access realm to core realm?

Hi guys,

I have a question about routing incoming calls from access realm (proxy registration to core realm). On sip-interface of access realm, I add all transport-protocol in sip-port, I.e. UDP 5060, TCP 5060, SCTP 5060 and TLS 5061. The SIP registrar is a Cisco VCS Cluster, e.g. vcsc.test.com, DNS SRV resolves to 2 hostsnames, e.g. vcsc1.test.com and vcsc2.test.com. Both vcsc1 and vcsc2 accept incoming SIP messages on UDP 5060, TCP 5060 and TLS 5061.

What I want to achieve is, maintenance the transport protocol from end to end, i.e. if the end points send SIP messages with UDP, SBC should forward it to VCS cluster with UDP, if the end points use TLS, SBC should forward it to VCS cluster with TLS. I know this can be done by setting up multiple realm, each realm has one session agent with different transport-method. However,  I can not set up different session agents with the same hostname, e.g. vcsc.test.com?  Also I would like to know if there is a better or easier way to do that.