Most OTP integration problems are not about sending the code — they are about the small decisions around it: how long it stays valid, how many attempts are allowed, and what happens when delivery fails. This checklist covers the decisions worth making deliberately before launch.
Before you launch
- Code expiry window is short and clearly communicated to the user (see OTP & Verification for typical ranges)
- A maximum number of verification attempts is enforced per code, not just per session
- A minimum interval is enforced between resend requests for the same number (SMS pumping protection)
- The code itself is never written to logs, analytics events, or support tooling accessible beyond what is strictly needed
- Message templates are checked against GSM-7/Unicode segment limits, especially for Arabic — see the SMS length and encoding guide or the segment calculator For ready wording, see OTP message templates.
Handling delivery failure
A code that never arrives is a support ticket waiting to happen. Decide in advance: does the user get a visible "resend" option immediately, or after a timeout? Is there a fallback channel if SMS delivery is reported as failed? Building this decision into the flow before launch avoids an awkward retrofit later.
Testing before go-live
- Test with both Arabic and English message templates, not just one
- Test the expired-code path, not just the happy path
- Test what happens when a user requests multiple codes in quick succession
- Confirm delivery-report handling triggers the fallback or retry logic you actually built, not just what you intended
Frequently asked questions
How many attempts should a user get to enter an OTP code?
There is no universal number, but most implementations cap it at a small number (commonly 3-5) per code before requiring a fresh code, to limit brute-force guessing.
Should I log OTP codes for debugging?
Avoid logging the code value itself, even in non-production environments. Log the fact that a code was requested/verified/failed, not the code.
What should happen if OTP delivery fails?
Decide this before launch rather than during an incident: a visible resend option, a fallback channel, or both.