How to Automate OTP Verification with the DUAL SMS API

Manually renting a number and copying a code is fine for a one-off verification. But if you verify accounts in bulk, run automated end-to-end tests, or onboard users programmatically, doing it by hand does not scale. The DUAL SMS API lets you rent numbers and fetch OTP codes entirely in code, so verification becomes just another step in your automated workflow — no manual clicks required.

This guide is aimed at developers. It covers what you can automate, the typical request flow, and the practical patterns that keep your automation reliable and cost-efficient in production.

What you can automate

The API exposes the same actions you would take in the dashboard, as simple HTTP endpoints you can call from any language:

• Checking your account balance before a job runs
• Renting a number for a specific service and country
• Polling for the incoming SMS code
• Reporting success or releasing the number on failure

A typical automation flow

Most integrations follow the same predictable pattern. First, confirm you have enough balance for the job. Next, request a number for the target service and country. Submit that number to the platform you are verifying, then poll the status endpoint at a sensible interval until the code arrives. Finally, use the code and either report success or release the number.

Designing the polling loop

Polling is where most integrations succeed or fail. Poll every few seconds rather than in a tight loop, set an overall timeout so a stuck request does not hang your pipeline forever, and exit cleanly the moment a code is received. The full request and response formats are documented on our API page.

Handling errors gracefully

Real networks and platforms are unpredictable. Treat documented error codes as expected events, not crashes: if a number fails, release it and request another. Build in a maximum retry count so a persistently failing service does not drain your balance or loop forever.

Best practices for reliable automation

• Add sensible timeouts and a capped number of retries to every job
• Always release numbers you no longer need so balance is used efficiently
• Log each step so you can diagnose failures after the fact
• Keep your API key in a secret manager, never hard-coded in source

Reliable automation is mostly about handling the unhappy path well — the happy path takes care of itself.

Next steps

Start with a single scripted verification to confirm your credentials and flow, then wrap it in your retry and timeout logic before running it at scale. See the API documentation for endpoint details, authentication, and example requests in popular languages.