Wonder if 2100 MHz was chosen because it's the only frequency common to all three carriers. So easier to have a joint site (with what looks like, at the very least, shared antennas). Really good to see joint builds happening across three carriers. I know of many examples overseas of two carriers sharing infrastructure (e.g. EE+H3G in the UK, VF+O2 in UK, Optus+VF in AU, old Telstra+H3G in AU, etc) but this is the first I've heard of three carriers. Well done to all involved.