When Does Broadband Stop Being Enough? A Decision Framework for the Leased Line Question
Photo: АрміяІнформ, CC BY 4.0, via Wikimedia Commons
Full fibre business broadband has transformed what small and medium-sized firms can expect from a connection. Speeds of 100Mbps to 1Gbps, symmetrical or near-symmetrical, at prices that would have been unthinkable a decade ago. So why do leased lines still exist — and why do businesses that upgrade to them rarely look back?
The answer lies not in raw speed but in four words that broadband marketing tends to gloss over: contention, guarantee, symmetry, and service.
Contention: The Hidden Variable
Consumer and standard business broadband is a shared product. Your provider sells the same capacity to dozens of premises, on the assumption that not everyone needs full speed at once. Contention ratios of 20:1 or even 50:1 are normal. At 2am on a Sunday, your line is magnificent. At 11am on a Tuesday, when every neighbouring business is pushing video calls and cloud backups, performance sags.
A leased line, by contrast, is uncontended — a dedicated circuit between your premises and the provider's core network. What you pay for is what you get, at 3pm on a Wednesday or any other time.
The SLA Difference
Standard business broadband typically carries a best-ethics service level: faults fixed within a few working days, perhaps sooner on premium packages. A leased line comes with a contractual SLA — commonly a 6-hour or 7-hour fix commitment, with service credits if the provider misses it. For a firm where an hour offline costs thousands, that distinction is the entire business case.
The Tipping-Point Scenarios
Through our conversations with SMEs, certain patterns reliably indicate it is time to step up:
Cloud-heavy operations. If your accounting, CRM, file storage and line-of-business software all live in the cloud, latency and contention stop being inconveniences and start being productivity taxes. A team of thirty staff waiting on a lagging ERP system burns real money.
Serious VoIP volumes. A handful of calls ride happily on broadband. Twenty simultaneous calls, plus video conferencing, plus a cloud contact centre, demand guaranteed upload capacity — and symmetrical throughput is where leased lines earn their keep.
VPN and remote-team loads. Firms running site-to-site VPNs or supporting dozens of remote workers via cloud desktops need consistent, predictable bandwidth. Burstable shared connections make performance a lottery.
Mission-critical uptime. E-commerce, logistics, financial services — if downtime has a direct revenue cost, the SLA alone justifies the premium.
The Numbers, Honestly Stated
A typical UK full fibre business package might cost £40–£100 per month for several hundred megabits. A 100Mbps leased line, installed, generally runs £250–£400 per month with construction fees amortised or waived on promotion. At the higher end, 1Gbps leased lines can exceed £600 monthly.
That is a three- to five-fold difference. Whether it is worth it depends on a simple calculation: what does one hour of degraded or lost connectivity cost your business? If the answer exceeds a few hundred pounds, the maths favours the dedicated circuit. If you are a ten-person office whose worst-case outage means rescheduling a meeting, it almost certainly does not.
When Full Fibremains the Right Answer
Plenty of well-run SMEs should stay put. If your team is under twenty, your cloud usage is moderate, your call volumes are light, and you have a sensible 4G/5G failover in place, full fibre with a good business package delivers 95% of the experience at a fraction of the cost. Do not let a salesperson convince you otherwise.
A Middle Path Worth Considering
Before committing to a leased line, ask providers about Ethernet over FTTP or enhanced business fibre products with raised SLAs and traffic priority. These hybrid options occupy the gap between commodity broadband and full private circuits, and for many SMEs they hit the sweet spot.
The decision, ultimately, is not about prestige or spec sheets. It is about matching a contractual guarantee of performance to the genuine cost of not having one.
