What is SDSL?

We’ve all heard of ADSL, but what in the world is SDSL? It stands for ‘symmetric digital subscriber line’, and if you read any other business broadband websites and see it written as ‘synchronous digital subscriber line’, then we’re right, and they’re wrong. Kidding… sort of! It can be written like that, but there’s really no need for it to be; ‘symmetric’ works just fine. If it’s not broken, why fix it, right?

So what is a symmetric digital subscriber line? It might not sound like it makes much sense (like most things in the business broadband world!), but it’s easier to understand when we look at it next to it’s brother – ADSL. ADSL is something most of us are a bit more familiar with. ADSL stands for ‘asymmetric digital subscriber line’, and, as you might be able to guess, there’s only really one big difference between the two: symmetry. One’s a beautiful, balanced peacock. The other’s a funky looking hermit crab.

DSL & Symmetry

So there’s two types of DSL that are somewhat common in the UK: ADSL, and SDSL. ADSL is probably what you’re used to – it’s where your download speeds are much faster than your upload speeds. Take a look at most BT business broadband and you can see this – download speeds of 17 Mbps, and upload speeds of just 1Mbps. It’s standard, really, but it’s not ideal for businesses. It means that if you’re using technologies that require a lot of upstream data, like video calls, you’re going to struggle along the way.

SDSL is pretty different. It guarantees that you’ll get the same upload speeds as download speeds. Sound familiar? It should! This is the same sort of thing you get from a dedicated leased line. You won’t get the same speeds as as leased line, but because SDSL is delivered over a single pair of copper wires, instead of fibre, you won’t pay as much as a leased line, either, so that’s good news for businesses on a budget.

The Rain on the Parade

Are you ready to be impressed? Well, I’m going to use my mind-reading powers to tell you what you’re thinking right now. ‘The advantages of a leased line, for a fraction of the cost? Sign me up!’. We wish we could, but things aren’t quite as simple as that. It’s reported that SDSL is available in less than 20 percent of the country, and this hasn’t been helped by BT retiring their SDSL service back in 2004 to focus on ethernet in the first mile (EFM). However, there are still some providers offering SDSL, so don’t give up just yet! Compare business broadband to see what sort of DSL services are available in your area.

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