This is Bell's transit network. Whilst technically the UBB is on the individuals and not what is transited, it is essentially what is being billed for.
Bell is claiming that it's links on the transit network are being crippled by heavy users. This may actually be true during busy hour. But in reality this shouldn't happen, as Bell can increase the bandwidth of most these relatively cheaply, as most are fiber. There are probably a few 100 that aren't fibered, causing the biggest problem.
But OK. The more I read about this, the clearer it becomes that the problem doesn't really exist at the moment. This is Bell's way of sabotaging the GAS product that it has been forced to sell by the regulator.
I hope this is a move that will force the independents to group together to purchase their own DSLAMS and transit. And then Bell faces much stiffer competition. In the UK, BT is facing real and consistent competition, thanks to our regulator getting tough in the last few years. BT now even have to allow competitors to lease it's ducting to roll their own fiber.
EDIT: I found this: http://www.vaxination.ca/crtc/ADSL_intro.pdf
Which suggests that the only bit that could conceivably have contention, which the wholesale customer does not control, is the connection between the DSLAM and the BAS. From the BAS's to their handoff PoP/CO, they have to pay for these "AHSSPI/AHSSL (Aggregated High-Speed Service Provider Interface/Link)" in 1gbps increments.
The ruling last year: http://www.crtc.gc.ca/eng/archive/2010/2010-802.htm
The result of consultation on the ruling, and dates for its application: http://crtc.gc.ca/eng/archive/2011/2011-44.htm
This affects the "Gateway Access Services (GAS)" customers. Wholesale Bell customers. (Product details here http://www.wholesale.bell.ca/pdfs/GASDSL.pdf)
And "Third Party Internet Access (TPIA)" customers. Rogers & Shaw Wholesale customers.
The GAS is not local loop unbundling. That is "(ADSL) Access Service" (http://www.bce.ca/en/aboutbce/regulatoryinformation/tarrifs/...)
There are essentially three options for an ISP. Diagrammed below.
PoP = Point of Presence. This is the handover from the access network to the provider network. The equipment found here is often called a BRAS.
Source: http://en.wikipedia.org/wiki/File:XDSL_Connectivity_Diagram_...