Ran the CSV through our deduper first. The phone column was live for 95% of the rows I tested. Bought it to underpin a United States fitness center campaign. Saved us hours of manual cleanup.
Did the job for our campaign. Dedup pass only flagged 1.2% — cleanest dataset I've worked with. Bought it for a United States-focused fitness center territory cut. One column I'd add next refresh: secondary email.