Uptime is how much of the time a service works, stated as a percentage. The percentages look similar and mean very different things: the useful way to read them is as an allowance of downtime rather than as a score.
Over a year, 99% permits about 3 days 15 hours of downtime; 99.9% about 8 hours 46 minutes; 99.99% about 52 minutes; and 99.999% about 5 minutes. Written that way the difference between three nines and four is obvious, and the difference between a marketing claim and a contractual commitment becomes worth checking.
The same percentage measured monthly and annually are different commitments. A monthly measurement resets the allowance every month, which is usually better for the customer; an annual one lets a single long outage consume the year. Check which applies.
Availability of the circuit is not availability of your service. A circuit that is up while your router is down is still counted as available, and correctly so. End-to-end availability depends on your equipment, your power, and your design — which is why organizations that need high availability build diverse paths rather than buying a bigger number.
Availability figures are almost always net of exclusions: scheduled maintenance, force majeure, outages caused by customer equipment or facilities, and time waiting for site access. Remedies are typically credits against the affected service rather than compensation for business impact, and they usually have to be claimed inside a stated window rather than being applied automatically. The exclusions and the claim process matter as much as the headline number.
Uptime figures are the most quoted and least examined numbers in telecom. Converting the percentage to minutes, checking the measurement period, and reading the exclusions turns a marketing claim into something you can evaluate.
Uptime is one of the specifications these comparisons turn on.
Describe the requirement and an engineer will tell you which service actually fits — without a rate card or a sales script in the way.
Service availability depends on location, network proximity, capacity, and engineering review. Share an address and we will confirm what can be delivered there.