OTP-as-a-Service: Automate Phone Verification for AI Agents

The Verification Bottleneck

Your AI agent can browse the web, fill out forms, and click buttons. But the moment a service says “Enter the code we texted you,” everything stops. Phone verification is the single biggest blocker for autonomous agents — and it's getting more common, not less.

Over 80% of online services now require SMS-based verification. Banks, SaaS platforms, social networks, e-commerce sites — they all gate access behind a 6-digit code sent to a phone number. For humans, this takes 5 seconds. For agents, it's an unsolved infrastructure problem.

Why Existing Solutions Fall Short

Manual SMS Services (TextVerified, LegitSMS, PVACodes)

Services like TextVerified, LegitSMS, and PVACodes rent phone numbers for one-time SMS reception. They work for manual use — you visit a website, rent a number for $3-4, and read the code from a web portal. But they're not built for programmatic automation:

• No real-time webhook delivery — you poll a web page
• No OTP extraction — you parse the raw SMS yourself
• Per-use pricing ($3-4/number) makes high-volume expensive
• Limited API support, designed for human operators

Raw CPaaS (Twilio, Telnyx, Vonage)

Twilio and Telnyx give you phone numbers and SMS APIs, but OTP extraction is your problem. You provision a number, set up a webhook, receive the raw SMS body, and write regex to parse the code. It works, but you're building plumbing instead of features. Plus, their VoIP numbers get rejected by strict verification services.

The AgentCall OTP Pipeline

AgentCall solves the full pipeline: provision a real SIM number that services accept, receive the SMS, extract the OTP code automatically, and deliver it to your agent via webhook — all in one API.

How It Works

1. Provision a real SIM number (passes strict verification)
2. Your agent enters the number on a signup form
3. The service sends an SMS with a verification code
4. AgentCall receives the SMS and extracts the OTP automatically
5. The OTP is delivered to your webhook with the sms.otp event
6. Your agent enters the code and completes verification

Full Automation Example with Playwright

import AgentCall from 'agentcall';
import { chromium } from 'playwright';

const client = new AgentCall({ apiKey: 'ac_live_...' });

// 1. Provision a number
const number = await client.numbers.provision({
  country: 'US',
  type: 'sim',
  label: 'signup-bot',
});

// 2. Automate the signup form
const browser = await chromium.launch();
const page = await browser.newPage();
await page.goto('https://example-service.com/signup');

await page.fill('input[name="email"]', 'agent@myapp.com');
await page.fill('input[name="phone"]', number.number);
await page.click('button:has-text("Send Code")');

// 3. Wait for the OTP (extracted automatically)
const otp = await client.sms.waitForOTP(number.id, {
  timeout: 60000,
});

// 4. Enter the code
await page.fill('input[name="otp"]', otp);
await page.click('button:has-text("Verify")');

console.log('Signup complete!');
await browser.close();

The entire flow — provision, signup, OTP extraction, verification — runs without human intervention. The waitForOTP()method blocks until a verification code is detected in an incoming SMS, then returns just the code.

Webhook-Based OTP (Event-Driven)

If your agent architecture is event-driven, use webhooks instead of polling:

// Register for OTP events
await client.webhooks.create({
  url: 'https://my-agent.com/otp-handler',
  events: ['sms.otp'],
});

// Your webhook receives:
// POST https://my-agent.com/otp-handler
// {
//   "event": "sms.otp",
//   "data": {
//     "messageId": "msg_abc123",
//     "from": "+18005551234",
//     "to": "+15551234567",
//     "body": "Your verification code is 847291",
//     "otp": "847291"
//   }
// }
//
// The "otp" field is pre-extracted — no parsing needed.

Why SIM Numbers Matter for OTP

Not all phone numbers are created equal. VoIP numbers from Twilio, Google Voice, and similar services are flagged in carrier databases. Many platforms — Stripe, WhatsApp, Uber, banks — silently reject verification SMS sent to VoIP numbers.

AgentCall's SIM numbers are issued by real mobile carriers. They appear as regular mobile numbers in carrier lookup databases, so they pass the same verification checks as a personal phone. This is the difference between “it works in testing” and “it works in production.”

OTP Extraction Under the Hood

AgentCall's OTP extraction handles the messy reality of verification messages. There's no standard format — every service sends codes differently:

• Your code is 847291 (most common)
• 847291 is your verification code for Acme
• G-847291 (Google style)
• Use 847291 to verify your account
• Verification code: 847291 - do not share

The extraction engine matches against dozens of patterns, ordered from most specific to least. It handles 4-8 digit codes, alphanumeric prefixes, and various message formats. The extracted code is delivered in the otp field of the webhook payload.

Pricing Comparison

For high-volume OTP automation, AgentCall is significantly cheaper than per-use SMS services:

• TextVerified: $3-4 per number per use. 100 verifications = $300-400.
• LegitSMS / PVACodes: $2-5 per number. Similar per-use pricing.
• AgentCall: $8/month per SIM number + $0.015 per SMS. 100 verifications on one number = $9.50/month total. The same number works for unlimited verifications.

FAQ

What services does AgentCall work with for OTP?

Any service that sends SMS verification codes to real phone numbers. This includes Google, Stripe, WhatsApp, Uber, banks, social platforms, and thousands of SaaS services. If it sends a text to a mobile number, AgentCall can receive and extract the code.

How fast is OTP delivery?

SMS typically arrives within 5-15 seconds of triggering verification. OTP extraction and webhook delivery adds less than 100ms. End-to-end, your agent gets the code within seconds of requesting it.

Can I use one number for multiple OTP verifications?

Yes. A single provisioned number can receive unlimited OTP codes. Unlike per-use services where you rent a number for one verification, AgentCall numbers are persistent — use them as many times as needed for $8/month (SIM) or $2/month (local).