There are now four Openreach products on FTTC, which are the only ones available to ISPs. 40/2, 40/10, the new 55/10, and 80/20.
The ISPs cannot advertise those speeds, as at least 10% of customers have to be able to achieve the advertised speeds. Hence we see 38/1.9, 38/9, 52/9 and 76/19 or similar on their websites.
40/20 never existed, but Plusnet sold it for a period. It was achieved by providing their customer with Openreach 80/20 but throttling the maximum download speed to 40Mbps within their own system. This seems to have been a marketing gimmick, but was financial madness. They were paying Openreach for the fast product and charging the customer exactly what they had previously charged for 40/10 - the 40Mbps product they had sold for a long time.
Needless to say, it didn't last long. But Plusnet, as usual, stood by their legacy product customers and kept on providing it to those who had signed up to it. At the same time as stopping selling it they reverted to the 40/2 product that they had started with several years ago.
Like TalkTalk, Plusnet currently do not sell 40/10.
As of 1 August this year they have finally decided they need to cut out the 40/20 product, so are replacing it with 55/10 for the customers still on it. They do not, it seems, intend at the moment to make 55/10 available to other existing customers or new ones.
There are no hardware restrictions that I'm aware of. Purely the Openreach price of each product for ISPs to buy and what they choose to sell it at. Taking into consideration all the other factors affecting our own choices of ISP, and profitability and desired market share.
Ah - there is one hardware factor, but not specifically down to this. The underlying providers at exchanges - BT Wholesale Sky, TalkTalk and Vodafone, have to buy from Openreach a GEA Cablelink to get the FTTC traffic from the Openreach exchange termination equipment to their own backhaul. The original one had a maximum throughput of 1Gbps and cost them £2000. They can now also have a 10Gbps one costing £10,000.
Given the huge increase in streaming bandwidth needs since FTTC first became available, it could be the higher speed ISPs wish to provide to customers will need them to upgrade their Cablelinks. Else have congestions at that point at times like Wimbledon and Euro football.
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