Basically, in your case yes. There's this old diagram
that will help. I'll deal with the changes to that first.
It's pre-LLU and pre-BT Wholesale WBC (the broadband part of 21CN).
The BT (strictly speaking BT Wholesale) ATM network is now a BT Wholesale Cloud. (Yuck - the modern name for network). For non-LLU ISPs the rest is roughly the same.
As you know, LLU ISPs have their own kit in the exchange. So add an "LLU" arrow from the exchange to "Your ISP". That's the basic diagram fixed.
Looking at LLU, in the exchanges where an LLU ISP doesn't have their kit, their traffic follows the normal route rather than going down our new arrow. Both TalkTalk and Sky used to sell both paths but have stopped putting any new customers on the BTW path. They still have legacy customers going that way. Orange also did that.
Now let's introduce BT Wholesale White Label. To include that we need a "White label" arrow from the BTW Cloud straight to "rest of the Internet". The ISP doesn't have any of the normal ISP's handover points fro the Cloud, no routers or internal network, and no links to the wider internet.
Orange/EE is now White Label. The Post Office started that way, but would have been paying the high BTW prices. So they contracted with TalkTalk, who don't forget cover nearly all the population with LLU, to provide a service to their customers instead.
For that large chunk of business TalkTalk provide LLU nearly everywhere, very cheaply for the Post Office, and fill in the gaps with the non-LLU path on the diagram. Bear in mind they still have some of the required kit to interface with the Cloud.
Both TT and Sky non-LLU services were dreadful in terms of the capacity per customer they rented from BTW, resulting in lousy performance. It looks as if similar is now affecting the Post Office in non-LLU areas.
Perhaps the PO are gaining customers in non-LLU places and the TT capacity hasn't been upgraded to handle that plus increased usage by their legacy customers. If that's the case it's up to the PO and TT to negotiate an increase. Unless TT aren't contracted to increase their core BTW capacity and don't intend to.
That would explain the PO Help saying within-term customers can leave without penalty. It's one way of slowly bringing things back into balance. So long as a big outcry from PO customers affected doesn't arise.
The indispensable man or woman passes from the scene, and what happens next is more or less the same thing as was happening before.
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