Normalize every number before screening. Prefer a consistent international country code plus local number with no embedded spaces, hyphens or parentheses. Keep only supported digits and, when accepted, a leading plus; place one number on each row.
The selected country or region must match the number's international code. Use one market per batch and split mixed-country lists before upload. Determine region from the code rather than a filename or note so a wrong global setting does not distort the whole result.
For hundreds or thousands of records, use a UTF-8 TXT or single-column CSV. Keep batches within manageable supported limits and reconcile imported count with the clean source. A large shortfall usually indicates blanks, formatting or delimiter problems that should be corrected before the paid or final run.
Deduplicate only after normalization so local and country-coded versions of one contact collapse correctly. Preserve a source backup and, when channel provenance matters, keep that metadata outside the unique screening key.
Run a preflight for country code, digits, blank rows, illegal characters, market, searchable task name and count. Pilot a few dozen records when possible before scaling.
After completion, download and archive registered, unregistered and indeterminate states under a date and batch identifier. Reconcile downloaded and submitted counts, document any difference and join results to source through the normalized number. Back up before upload, archive after download and remove duplicates every time.
