BT’s Openreach infrastructure division, which will soon escape from the BT mothership with some 32,000 employees under its twisted copper arms and form a separate company, has released a 360-degree walkthrough video of a modern telephone exchange. This is somewhat unusual: there are low-res photos of telephone exchanges online, and some historical illustrations of telephone exchanges for educational purposes, but a high-res walkthrough of an active exchange is quite rare.
The first thing you’ll notice is just how tidy the room is. It looks like a server room, or perhaps even a small data centre, with very few exposed wires and some nice overhead ducting. Unlike a data centre, though, natural light floods in through some windows (I expected more security, really). Sadly we don’t know the location of the exchange, but judging by the size of the car park outside, the building presumably houses more than just an exchange. (An area code on one of the printed signs suggests the exchange is somewhere in Bedfordshire.)
The first half of the room mostly consists of equipment hidden inside cabinets. We don’t know exactly what’s in there, but it’s probably a bunch of third-party-owned DSLAMs (digital subscriber line access multiplexers) from the ADSL providers that operate in the area (Sky, TalkTalk, etc.) If you want to mentally fill in some of the gaps, Kitz.co.uk has a few photos from 2008 that give you a rough idea.
The second half of the room features the main distribution frame (MDF). The side nearest the wall is the D-side (distribution side) where external telephone lines first enter the system; the backside of the MDF is the E-side (exchange side), where the telephone lines are then fed into various pieces of equipment. The Openreach engineer points out some ISDN blocks and DACS blocks (an old tech that multiplexed multiple phone lines over a single twisted pair). To left of those are the ADSL blocks, which would then be connected to the aforementioned DSLAMs.
One thing that you won’t see in the Openreach telephone exchange is VDSL (“superfast broadband”) equipment. That equipment is instead much closer to your house, inside or next to a PCP (a primary connection point, aka a streetside green cabinet). From the cabinet, your Internet traffic travels via optical fibre to the telephone exchange, and then onto BT’s core network. There will be a fibre backhaul router somewhere in the exchange, but it doesn’t seem to be visible in the walkthrough video.
In addition, Openreach yesterday released a 360-degree video of an engineer inspecting a green cabinet (embedded below), but unfortunately there’s no FTTC or VDSL equipment in there. There’s also a 360-degree clip from the top of a telephone pole, and a rather dull look inside an Openreach van.
These 360-degree videos, according to an Openreach press release, are part of a recruitment drive: the soon-to-be-separated company says it wants to hire and train 1,500 new engineers, with the hope of reducing the time it takes to install and fix problems on the network. Poor customer service was one of the key reasons behind Ofcom pushing for BT and Openreach’s separation.
If the telephone exchange walkthrough piqued your interest, read our in-depth explainer of how the Internet works…
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