Minimum Guaranteed Download Speed Explained
estimated read time: 4 minutes
Tracking Internet Service Provider Performance
Why?
Before 2020, homeworking was a luxury afforded to few. Even within the IT sector, the norm was to go into the office. Offshore and nearshore staffing were common, but spending weeks at home was not the default.
COVID-19 lockdowns changed everything. The home became the primary workplace, and suddenly employees—not employers—were responsible for maintaining their own IT infrastructure. Networking shifted from a concern for the technically minded to a household issue. Home internet transformed from an entertainment asset, like your TV licence, into a vital commodity, like electricity or running water.
As the pandemic rolled into 2023, with lockdowns over a year behind us, life returned to normal. Yet many chose to stay at home, preferring the work-life balance that remote working offers.
Earlier this year, I gave a talk on Service Level Objectives, emphasising the importance of “monitoring what matters”. It was then that I thought:
“Why am I not monitoring what matters at home?”
My average working week is 45 to 50 hours, all spent on a computer connected to VOIP calls or messaging platforms—entirely dependent on my single ISP. I’d already upgraded from 30Mbps to 1Gbps, but how would I know if I was actually getting what I paid for?
I started digging. What protections exist for British consumers when holding an ISP accountable?
Thankfully, Ofcom—the UK’s communications regulator—had already started addressing this. Back in 2018, they introduced a voluntary code of practice for broadband information. This policy requires signatories to provide:
- More realistic speed estimates at the point of sale
- A minimum guaranteed speed, with the right to exit if not met
- Strengthened customer rights, extending exit rights to bundled products
- Equal benefits for all customers, regardless of broadband technology
With any luck, my ISP had signed up. After a bit of digging, I found the list of participating providers. As the table below shows, some common vendors have not yet signed up.
| Vendor | Has a Minimum Guaranteed Speed Policy? | Minimum Guaranteed Speed |
|---|---|---|
| BT | Yes | Policy Link |
| Sky Broadband | Yes | Policy Link |
| Virgin | Yes | Policy Link |
| EE | Yes | Policy Link |
| Plus Net | Yes | Policy Link |
| Talk Talk | Yes | Policy Link |
| NOW Broadband | Yes | Policy Link |
| Utility Warehouse | Yes | Policy Link |
| Zen Internet | Yes | Policy Link |
| Vodafone | No | |
| KCOM | No | |
| Three | No |
The Three-Day Rule
All signatories to the Ofcom code of practice effectively agree to:
“Right to exit the contract without penalty where speed problems cannot be resolved.”
Whilst that’s rather vague, signatories also agree that the maximum download speed quoted at point of sale must be at least 50% of the advertised speed, including during peak times. If you purchase a 100Mbps connection but only receive 40Mbps—and can’t physically move closer to the exchange—you can rely on your personalised minimum speed guarantee to be released from the contract.
That said, internet speeds fluctuate. A momentary dip to 20Kbps doesn’t entitle you to exit. The general rule of thumb is the “three-day rule”: after three consecutive days below your Minimum Guaranteed Speed, your right to leave kicks in. Check your provider’s specific policy for details.
How to Track Your ISP
In previous posts, I’ve discussed setting up a Kubernetes cluster in a home lab. For this solution to work, you’ll need a cluster to run the stack on.
I’ve created a small open-source project to help with this—see my GitHub repository: isp-monitor. It creates a dashboard that, at the time of writing, is configured for my ISP. As the project evolves, I’ll make it more configurable.