@twentypoint4, same as "old" system at PC, ITEC uses Mode S
This retired crusty used Mode S often, especially on the quieter West Coast sector when you get to know the regular customers who select 7000 but often monitor the frequency only, calling them to find their intentions made UK FIS services to other customers a lot easier.
Also, nice to see the Mode S greetings from a few Loganair crews at XMAS and NY !