Last update 7 April 2011
LLU - Local Loop Unbundling - is when an ISP (or more correctly a Communications Provider in current BT-speak) has installed its own equipment in your exchange.
At the exchange broadband lines coming in from the customer are connected to either a DSLAM, or in the case of BT 21CN broadband an MSAN. So BT Wholesale have theirs, and LLU ISPs have their own.
Note that the line from the user premises to the exchange and on to the DSLAM/MSAN is always BT OpenReach property and responsibility. A “BT” line as required by most ISPs means that BT Wholesale rent it from OpenReach. CPs (as distinct from ISPs) then rent it from BT Wholesale. This is called WLR (Wholesale Line Rental), quite independently of the broadband provision on the line, though CPs may choose to restrict the broadband to just their own products
For example BT Retail, Sky non-LLU and The Post Office allow other ISPs on their WLR lines, Plusnet (for new phone connections) and O2 do not.
Most or possibly all LLU ISP DSLAMs are 24Mbps-capable (ADSL2+). These ISPs normally offer “up to” 16, 20 or 24Mbps packages, as well as rate-capped 8Mbps ones at a lower price as direct competition with BT-based 8Mbps products.
Because they have their own equipment in the exchange and arrange their own backhaul from there to themselves, even though they may use BT connectivity to do that, they are released from the pricing structures of BT Wholesale IPStream/DataStream/WBC/WBMC/IPSC. They can therefore offer broadband far cheaper than those ISPs who use BT Wholesale, and some are also now offering wholesale services to other ISPs in the same way as BT Wholesale do.
Importantly, there are two sorts/kinds of LLU. Full LLU (technically called Metallic Path Facility or MPF) is where the CP takes complete control of your phone service as well as the broadband. The main examples that spring to my mind are TalkTalk and in many cases Sky, although as I understand it both also supply BT Wholesale products in some situations.
Partial LLU, (Shared Metallic Path Facility or SMPF) is where the phone service stays with BT Wholesale (billed to you by BT Retail or the Post Office or one of several others), but the broadband is provided by the LLU CP.
Examples being O2/Be, Cable & Wireless and Sky, see above. In the past Sky LLU broadband was SMPF but new customers are wherever possible being put onto MPF. More information.
What isn’t commonly known is that with all ADSLx connections the customer’s line is connected to the broadband DSLAM/MSAN, and the telephone service at the exchange end is also connected to the DSLAM/MSAN in order to get to the customer’s line.