What it detects
- Real allocation, not just correct length
- VoIP and disposable numbers
- Premium-rate numbers
- Toll-free and shared-cost lines
- E.164 normalisation, 240+ countries
- NANP area-code allocation
When to use it
Before sending an SMS verification code — a premium-rate number bills you, not them.
Questions
Why does premium-rate detection matter so much?
It is one of the few fraud signals with a direct, immediate cost. If you send an SMS verification code to a premium-rate number, you pay the premium — the attacker is not evading a check, they are billing you. Catching it before the send is the whole point.
Can you tell me if the phone is switched on?
No, and be sceptical of anything claiming to do that cheaply. This validates against numbering-plan allocation and line type, which is real and useful and needs no network query. Live reachability requires an HLR lookup — a different, far more expensive product.
Why is it so fast?
It runs entirely offline against libphonenumber metadata. No carrier API, no round trip, no per-lookup data cost — which is also why it is included at every tier rather than priced separately.
How to do this
Step-by-step, with the trade-offs named.