A regression test for registration and account recovery loses its point if every run gets a new number: the scenario checks the input form, not what actually happens to a real account on a repeat sign-in through the same contact. Offline number rental solves this differently — the test harness gets a slot that stays the same from run to run, and airtime comes online only for the time it takes to receive a code. Here is why a test harness needs a persistent number, how many slots regression needs, how to plan airtime around a run, and when a paid package becomes necessary.
Why a test harness needs a number that does not change
An end-to-end scenario — registration, confirmation, repeat sign-in, account recovery — depends on the account number staying the same across steps. A mocked code checks the form, not the chain itself: code delivery to the test harness, binding the number to an account that already exists, repeat verification during password recovery. These steps only reproduce on a real code that actually arrives at a number genuinely assigned to the tests, not one substituted directly into the scenario.
Why a one-off activation does not suit regression
A one-off activation sells a code, not a number: once received, it is released, and the next run gets a different contact. A recovery scenario for an existing test account on a new number every time does not reproduce — regression needs exactly a repeat sign-in through the same contact the account is already bound to. An offline slot solves this because the number stays assigned for the whole paid ownership term — a day, 3 days, a week, a month, 3 months or half a year — and the same scenario can run on it every day if needed.
How many slots to keep for a test harness
The number of slots follows the number of parallel scenarios, not the run frequency: registration, two-factor checks, account recovery and number change are at least four independent contacts, if tests should not compete for the same slot. Each slot gets a fixed free airtime window per day — an hour, up to twice — and that limit covers one or two short regression runs a day for one scenario, as long as the code arrives quickly and predictably; more frequent runs are cheaper to cover with a paid package from the start.
Planning airtime around a regression run
The slot needs to come online ahead of time, not the moment a test is already waiting for a code: an SMS sent to an offline number does not arrive, and after coming online a slot needs time to register on the network before the channel is ready to receive messages. A practical pattern is bringing the slot online a few minutes before the scenario starts and keeping the window open for the whole run, instead of splitting it across each individual test step.
Isolation from production numbers and when a paid package is needed
Test slots should come from a separate pool, not the numbers assigned to production accounts: mixing them confuses cost tracking and risks a regression run grabbing the airtime of a number waiting for a production code at that exact moment. Free windows are enough while regression fits into one or two short sessions a day. When a run is long — a full CI suite before a release stretches into hours, not minutes — two hourly windows, that is two hours of airtime per slot a day, will almost certainly not cover it, and a guaranteed airtime package for 1, 3, 6, 12 or 24 hours is needed noticeably more often than before: for that time the channel stays online without interruption and skips the queue that other slots' free windows are subject to.
Frequently Asked Questions
Can regression run every day on the same offline number?
Yes, that is the whole point of the scheme: the slot stays assigned to you for the whole paid term, and the same number takes part in the scenario as many times as needed, not once per run the way a one-off activation works.
What happens if a test does not finish within the free hour?
The slot goes offline and the code stops arriving — other windows remain within the daily limit, or for a long run it is worth buying a guaranteed airtime package in advance so the channel does not close mid-scenario.
How do I know free windows are enough for a test harness and a paid package is not needed?
If regression fits into one or two short one-hour sessions a day and you can plan the window ahead for an expected code, free windows are enough; a paid package is for long, continuous runs where waiting for the next window is not an option.
A set of slots for a test harness with free windows and guaranteed airtime packages is available in the offline SMS rental section. How slot ownership and free windows work is covered in what is offline number rental, end-to-end runs with real codes in CI are covered in automated tests with real codes, and how to keep production data out of a test stand is covered in test data. Choosing a paid package's length for a specific run is covered in how to choose guaranteed airtime length.