Most verification failures are formatting-related, not inbox-related. Use international format (country code + digits), avoid spaces/dashes, and don’t add an extra leading 0.
Best default format: +CountryCode + Number (example: +14155550123)
If the form is digits-only: CountryCodeNumber (example: 14155550123)
Simple OTP rule: request once → wait 60–120 seconds → resend only once.


Russia
USA
Nigeria
Germany
Canada
Slovakia
Morocco




























