Bad phone numbers cost money — failed OTP deliveries, undelivered SMS marketing, wasted call-centre time and fraudulent sign-ups. The AutoPostcode phone validation API catches them at the point of capture, so you only store numbers you can actually reach.
See it in action
A live HLR lookup confirms a real, reachable SIM — or flags numbers you should never send to.
Valid mobile
Active SIM · carrier detected
VoIP / disconnected
Caught before you spend on SMS
What the API checks
- Structural format against the country's numbering plan
- Line type: mobile, landline or VoIP
- National and international (E.164) formatting
- Live carrier and network connectivity via HLR lookup
- Number portability — has it moved networks?
- Country detection and normalisation
Two levels of verification
Choose the depth you need per request. A format check is instant and cheap; a live check reaches into the mobile network to prove the number is active right now.
Format validation — 1 credit
Instantly confirms the number is well-formed for its country and returns the line type and clean formatting. Ideal for inline form validation as the user types.
Live HLR validation — 2 credits
Adds a Home Location Register (HLR) lookup that pings the carrier network to confirm the SIM is active, returns the current carrier, and flags ported numbers. This is the only reliable way to detect disconnected numbers before you send.
Example response
{
"phone": "+447700900123",
"valid": true,
"verdict": "valid",
"country": "GB",
"line_type": "MOBILE",
"national_format": "07700 900123",
"international_format": "+44 7700 900123",
"live": { "connectivity": "CONNECTED", "carrier": "EE", "ported": false }
}Where teams use it
- Verifying mobile numbers before sending OTP / 2FA codes to cut SMS waste
- Cleaning contact lists so campaigns don't burn spend on dead numbers
- Blocking fake or VoIP numbers at sign-up to reduce fraud
- Confirming delivery contact numbers for couriers and field service
One API key for every check
Phone validation shares a single API key and credit pool with postcode lookup, email validation and bank account validation. Add data-quality checks across your whole stack without juggling multiple vendors or contracts.
Frequently asked questions
What does the phone validation API check?
Format validity, country, national and international formatting, and line type (mobile, landline, VoIP). With live=true it performs an HLR network lookup that returns real-time connectivity, the current carrier and whether the number has been ported.
What is the difference between format and live (HLR) validation?
Format validation is instant and costs 1 credit — it confirms the number is structurally correct and identifies the line type. A live HLR check costs 2 credits and pings the mobile network to confirm the SIM is active and reachable right now, which is the only way to catch disconnected or dead numbers.
Does it work for international numbers?
Yes. The default country is GB, but you can pass any country code and the API normalises the number to E.164 international format and validates it against that country's numbering plan.
How much does phone validation cost?
1 credit per format check, or 2 credits when you enable the live HLR network check. Credits come from the same shared pool as postcode lookup, email and bank validation — one API key, one balance.
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