What is SDSL?

SDSL stands for ‘symmetric digital subscriber line sdsl’. Its the upgraded brother of ADSL which is the traditional copper broadband we all know & experience buffer rage with. ADSL stands for asymetric digital subscriber lines & uses copper telephone lines to deliver your internet connection.

Symmetric digital subscriber lines are different to ADSL. The main difference between the two: symmetry. SDSL gives you symmetrical upload and download speeds, much like the business class leased line, only less reliable.

Whats is the difference between SDSL & ADSL?

The two types of DSL that are common in the UK: ADSL, and SDSL. ADSL is what you’re used to. It has faster download data rates and the bandwidth degrades over distance. Take a look at most BT business broadband – download speeds of 17 Mbps, and upload speeds of just 1Mbps.

Understandably those speeds are 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 different from standard broadband connections. It guarantees that you’ll receive the same upload speeds as download speeds. The other business grade connectivity that offers this symmetry is an Ethernet leased line.

SDSL will not provide the same high speeds as as leased line, but because its delivered over pairs of copper wires, instead of fibre, you won’t pay as much. This makes it a better option for smaller businesses with limited connectivity budgets.

Availability in the UK

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.

Its not always a fraction of the cost & It’s reported that SDSL is available in less than 20 percent of the country.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 it.

The majority of UK providers & businesses have moved away from single pair SDSL and DSL connectivity in general due to the increase of fibre availability. Fibre is a more robust, reliable and faster connection than copper & doesn’t degrade over distance.

The cost

The cost of SDSL starts from £150 per month so they are similar to leased line costs anyway. When SDSL was first available and the business world was introduced to a lower cost internet that can give you symmetrical uploads and downloads – it was seen as groundbreaking technology.

However, its 2019 & the cost of leased lines have fallen dramatically since then. DSL connections with the same upstream and downstream data often have lower speeds than a leased line which makes running things like online voice services less reliable. The speed also reduces over distance so if you are further away from the providers pop you will get a lower bandwidth internet connection.

Conclusion

SDSL was a proprietary technology when it first entered the market. Especially as it was seen as a better asymmetric digital subscriber line adsl technologies replacement. In 2019 its on its way to becoming a legacy service with less people using it than before. Technology moves at such a quick rate & the reduction of leased line costs and lack of availability has seen more businesses move to their own dedicated fibre line.

If you are considering SDSL we would love to help assess you options & compare all types of business broadband & connectivity.