What it actually means
A leased line is a private fibre circuit that runs from your premises to the wider internet, used by your business and nobody else. That word, dedicated, is the part that does the heavy lifting. On a normal business broadband product you share capacity with other premises in the area, so peak time slowdowns are a real thing. On a leased line, the bandwidth you buy is the bandwidth you get at three in the afternoon on a Tuesday and at the start of payroll on a Friday.
The other defining feature is symmetry. Upload speed equals download speed, which matters the moment you start backing up to the cloud, running video calls, hosting your own systems, or relying on VoIP for inbound sales. Leased lines come in tiers from around 10 Mbps up to 10 Gbps and they are sold with an SLA covering uptime and repair. Install typically takes 30 to 90 working days because Openreach has to survey the route, sort wayleaves with landlords, and physically dig where needed.
In business
What this looks like at work
The felt cost shows up in the moments you can least afford it. A frozen video call halfway through a pitch to a new client. The CRM stalling while a sales agent sits on hold to their own prospect. A warehouse scan that keeps timing out so the courier waits in the yard with the engine running. Standard shared broadband can handle the average day, then buckle on the day that pays your wages. A leased line takes that variable out of the operation. You quote a customer a delivery slot knowing your systems will be up, you sign off a build knowing the architect can upload the file before five, and you stop budgeting around the connection as a risk line.