As ejs says WBC/WBMC is 21CN.
20CN exchanges are provisioned as
IPSC which took over from the old IPStream by joining the 21CN core at the bRAS.
Problem with 20CN is the lack of bandwidth on the backhaul link between the exchange and the bRAS.
Many of those links are decades old and originally ever intended to cope with speeds of much more than 2Mbps. The lack of available bandwidth is what in theory makes those exchanges more expensive. I'm sure some of us here can remember when it actually cost £1 per each GB of bandwidth on the old backhauls.
Upgrading to 21CN uses a much newer technology called
WDM which allows the same backhaul to have a heck of a lot more available bandwidth. In a way WDM is to fibre as to what dsl is to copper when compared to dialup, because it can split the backhaul fibre into different channels. It mutliplexes the fibre in a similar way as to how dsl uses FDM/DMT to multiplex on copper and thus more available bandwidth for fibre.
Whilst WDM equipment is becoming cheaper, D-WDM which is needed for the long distances of the backhaul, is still quite expensive to equip and install.
So where am I going with this?
1) Plusnet IMHO are wrongly charging for some connections because FTTC takes its feed from the headend exchange and not the local exchange.
2) Its about time that OFCOM de-regulated _ALL_ exchanges and stopped this Market pricing nonsense which OFCOM caused. The LLU ISPs have had more than enough time to decide which exchanges they want to install their own backhaul to, and if they havent done so by now then they are unlikely to do so any time soon, especially when FTTC is always fed from a larger 21CN exchange.
It's yet another case where OFCOM regulation is now over complicating things, and in this particular case there is no longer any need for them to butt their nose in something which doesn't benefit the EU. If they de-regulated the remaining exchanges and stopped the price differential, then it may encourage BT
w to upgrade those remaining 20CN sooner.