Real checkpoints in West Africa and a sovereign hub in the EU. You pick which ones per monitor; the choice doesn't add to the cost.
Checkpoint public IPs are published so you can allow them in your firewall / WAF.
An outage is confirmed by quorum: at least min(3, n) checkpoints must see the failure before you're alerted. A single checkpoint's local error is never taken for an outage.
See Kolosili on your own services, with your own checkpoints. A 20-minute demo is enough.