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Stop SMS pumping before it inflates your bill

SMS pumping quietly runs up your OTP bill. Validate every number's line type, carrier, and country before you send the code, and block pumping traffic before the message goes out.
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https://phonevalidation.abstractapi.com/v1/
    ? api_key = YOUR_API_KEY
    & phone = 14154582468

{
    "phone": "14154582468",
    "valid": true
    "risk_score": 0.1,
    "registered_location": "San Francisco",
    "carrier": "Verizon USA",
    "line_type": "Mobile",
    "local_format": "4154582468",
    "international_format": "+14154582468",
"country_prefix" : "+1",
    "country_code": "US",
    "country_name": "United Stated of America"‍
}

phone number validation api

{ "phone": "+15550100200", "valid": true, "type": "voip", "carrier": "Twilio", "country": "United States", "is_disposable": true, "is_abuse_detected": true }

The signals that expose an SMS pumping attack

Flags VOIP and premium-rate line types — the numbers pumping fraud targets.
Returns the carrier and country so you can block destinations you don't serve.
Adds phone risk flags like is_abuse_detected to catch known-bad numbers.
Runs in real time on every OTP request and stores nothing after. SOC 2 compliant.
Trusted to stop SMS pumping by teams at
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4.8 from 1,863 votes
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How an SMS pumping attack works

Every request resolves in real time and returns structured data in under 300ms.
A bot hits your signup form
Attackers script fake signups that each request an SMS verification code.
Codes route to premium-rate numbers
The numbers belong to ranges the fraudster and a rogue carrier control, so each send earns them a cut.
Your OTP bill inflates
You pay for every message while conversions stay flat; validating the number first stops the send.
Phone validation
Confirms a phone number is valid and returns its carrier, line type, and country.
IP geolocation and risk
Maps an IP to its location and network, and flags VPN, proxy, and other risk signals.
Real time, not static
Every field is fetched at request time from current sources, not served from a stored snapshot that ages between refreshes.
Validate every number through the API
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4.8 from 1,863 votes
Check line type, carrier, and country risk before you send the OTP, in one API call.
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No credit card required

Why teams stop SMS pumping

Validate before you send
Check every number's line type, carrier, and country before the OTP goes out, so pumping traffic never triggers a paid message.
Filter by destination country
Reject verification requests to country codes and carriers you don't serve, cutting off the routes attackers exploit.
Block VOIP and premium-rate lines
Flag the VOIP and premium-rate ranges that pumping fraud relies on, and reject them at the verification step.
Rate-limit and score the source
Combine phone risk with IP signals to catch bursts of requests from data-center IPs and bots before they inflate your bill.
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Spammy signs up were an issue for us for a while, and we struggled to come up with the best way to identify all the variations in bad emails we were getting. Thankfully we found and quickly integrated with Abstract's email validation API, which saved us a bunch of time and gave us peace of mind.
Chris Stanley, Scope

Frequently asked questions

What is SMS pumping?

SMS pumping is a fraud where bots trigger large volumes of one-time-password (OTP) and verification texts to phone numbers on premium-rate ranges the attackers control. They collect a share of the inflated messaging fees while you pay the SMS bill. It is also known as artificially inflated traffic, or AIT.

How do I know if I am a victim of SMS pumping?

The tell-tale sign is a sudden spike in SMS or OTP costs with no matching growth in real signups or conversions. You may also see a surge of verification requests to unusual country codes or carriers, and high send volume with low completion rates. If the messaging bill jumps while activations stay flat, suspect pumping.

What is artificially inflated traffic?

Artificially inflated traffic, or AIT, is the term SMS providers such as Twilio use for SMS pumping. Bots generate fake verification traffic to premium-rate numbers so fraudsters and rogue carriers can collect the revenue share. It is the same attack: real-looking OTP requests that exist only to run up your messaging costs.

How do you prevent SMS pumping without blocking real users?

Validate each phone number before you send the OTP rather than blocking traffic after the fact. Check the line type, carrier, and country, then reject VOIP and premium-rate numbers and destinations you do not serve, and rate-limit repeat requests. Real users on normal mobile numbers pass through untouched.

How much does SMS pumping cost?

It adds up fast. Multiply your per-message price by the flood of fake sends: at a few cents per OTP, an attack sending tens of thousands of messages can cost thousands of dollars in a single day, on top of skewed conversion metrics and the engineering time spent chasing the spike.

What is OTP fraud?

OTP fraud is any abuse of one-time-password flows. SMS pumping is the most common form, where bots trigger OTP texts purely to generate premium-rate traffic. It can also include intercepting or social-engineering codes to take over accounts. Validating the number before sending the code stops the pumping variant at the source.

How does Abstract help stop SMS pumping?

Call Abstract's Phone Validation API when a user requests a code. It returns line type, carrier, and country plus risk flags, so you can block VOIP, premium-rate, and out-of-market numbers before a message is ever sent. It is a single request, and you can start on the free tier with no credit card.

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