Yeah, the Royal Signals would have been a better forum.
However....you need to be aware that Info Sys Engr is no longer available. It's now Comms Sys Engr. Both are equally employable outside the mob and both are excellent trades. If you want to work with comms infrastructure like fibre optic cables and copper cables, connectors and tools then go Inst Tech. It's a great hands on trade with options to get down and dirty. If you want to work with radio systems, IT kit, multiplexers, routers and switches then it's the Engr trade all the way - basically ICT and Telecoms systems engineer.