SMS verification numbers for developers and QA
Testing an SMS flow properly means actually receiving an SMS. Mocking the provider tests your code; it does not test whether the code arrives, how long it takes, or what happens when it does not.
What test SIMs cost you
A physical test SIM is a recurring bill, a device to keep charged, and a manual step in an otherwise automated pipeline. Worse, it is one number — so every test run pollutes the same account state.
Virtual numbers remove all three problems. Each run takes a fresh number, verifies against it, and lets it go.
Fitting it into a pipeline
The SwiftSMS API issues a number, then exposes the messages that arrive on it. A test requests a number, drives the sign-up, polls for the code, asserts, and moves on. Nothing is charged when no code arrives, which means a failed delivery costs nothing but a red test.
- End-to-end sign-up coverage across countries, not just one home market
- Regression tests for OTP expiry and re-send behaviour
- Recovery-flow tests that need a second, different number
Testing internationally
Delivery behaviour differs by country in ways that never show up on a single test SIM — different latencies, different sender IDs, different truncation. Running the same suite across several countries surfaces the failures your users in those countries are already hitting.
