Inter Cluster Trunks (ICT)

I'm currently reading through the section regarding inter cluster trunks in the SRND guide. More specifically H.323 and SIP trunks between Unified CM Clusters. Nothing to detailed and pretty high level overview on recommendations regarding ICT's directly between clusters or using a Gatekeeper. I also went over high availability, load balancing, and the newer features that CUCM 8.x offers. I'm still drawing up what my CCNP: Voice lab is going to be or even if I decide to go for the cert still. VoIP is growing so fast and there's a multitude of different vendors out there, especially with SIP, it's hard to imagine spending 1k-3k for a very vendor specific certification. We'll see though